Ординатура / Офтальмология / Английские материалы / Small Incision Cataract Surgery (Manual Phaco)_Singh_2002

retinopathy is still possible postoperatively in lasered patients and it depends on the stage of diabetic retinopathy and the status of retina in these cases.

RETINAL DETACHMENT

FOLLOWING CATARACT SURGERY

Introduction and Epidemiology

Eyes with aphakia or pseudophakia account for more than 40 per cent of the total retinal detachments operated at any large referral centre. The incidence of retinal detachment is 2 to 5 percent after intracapsular cataract extraction and 0 to 1.4 percent after extracapsular cataract extraction. However, the incidence may approach 20 percent in cases with vitreous loss. YAG capsulotomy is risky in that the chances of retinal detachment increase threefold after the capsulotomy. The incidence of postoperative detachment is substantially increased in myopic eyes. 50 per cent of retinal detachments occur within the first year after cataract surgery. Retinal detachment may be present preoperatively in an eye undergoing cataract extraction or it may develop in the postoperative period.

Approach to Management

In all cases of cataract, where the fundus is poorly visualised by an indirect ophthalmoscope, it is imperative to get an ultrasound of the posterior segment done so as to rule out a retinal detachment. In case a retinal detachment is detected on the ultrasound, it is best to refer the case for a vitreoretinal surgery. Alternatively the case may be considered for a small incision cataract surgery (phaco or manual). Extracapsular cataract extraction should be avoided in such situations since the integrity of the corneal wound is not established for atleast 4 to 6 weeks following the surgery. A phacoemulsification has the advantage of permitting scleral buckling or primary vitreoretinal surgery in the same sitting or soon after the cataract surgery as the wound integrity is well maintained. A similar advantage exists to a lesser extent following a small incision manual cataract surgery. Retinal detachments detected preoperatively in a patient who needs cataract surgery are best handled with a primary vitreous surgery if fundus visualisation is poor or by an indirect ophthalmoscopy after removing the cataract (but prior to insertion of the IOL). In case the vitreoretinal surgeon concludes that the retinal detachment is relatively fresh and amenable to a scleral buckling procedure, one could consider insertion of a large diameter 6 mm IOL (not of silicone) If however, the retinal detachment is old or with

proliferative vitreoretinopathy (PVR), it is better not to insert an IOL.

Retinal detachments following cataract extraction typically have small flap tears along the posterior margin of the vitreous base. The retinal detachments are usually more extensive and often involve the macula. Multiple breaks are found in more than 50 percent of retinal detachments that occur following cataract extraction. The progression to proliferative vitreoretinopathy is also faster in such cases. These cases are managed like all other rhegmatogenous retinal detachments, with a scleral buckling surgery. In some cases it is difficult to find the break in cases of post cataract surgery retinal detachment, even with indentation because apart from the fact that the breaks are small and peripherally located, visualisation is also often difficult in many cases due to the presence of peripheral capsular opacification, and reflexes from the IOL edge.

The intra-operative visualisation of the fundus may also be hampered by the IOL edge or posterior capsule opacification, The corneal wound may need strengthening before starting the retinal detachment surgery. Even corneal/ scleral valves need to be strengthened most of the times, as they are not watertight under higher pressures, which are often reached when the eyeball is being manipulated. It is also important for the anterior segment surgeons to know that the possibility of subluxation or dislocation of the IOL always exists during a scleral buckling or vitreous surgery.

Prognosis following aphakic or pseudophakic RD surgery is at best fair. Patients with anterior chamber IOLs have a lower probability of reattachment after one procedure than do patients with posterior chamber IOLs. In recent times, anatomic success rates of upto 85 to 90 per cent are being claimed following RD surgery in post cataract surgery patients. The visual outcome in these patients may be subsequently occasionally complicated by cystoid macular edema, which further jeopardises the final visual acuity obtained by these patients.

POSTCATARACT SURGERY ANTERIOR ISCHAEMIC OPTIC NEUROPATHY (AION)

Anterior ischemic optic neuropathy was first described in 1951. Towne first reported four cases of optic neuropathy after uncomplicated cataract extraction. In 1973, Carroll reported the occurrence of AION with visual loss 4 weeks to 15 months after cataract surgery. In 1980, Hayreh described visual loss after cataract surgery that was thought to be secondary to ION. Risk factors for the

development of nonarteritic ION include hypertension, diabetes, smoking, and a crowded disk with a small cup, especially if the patient had a crowded disk in both eyes.

Pathogenesis

Hypotheses to explain the infarctive processes associated with both the anterior and posterior forms of optic neuropathy (AION and PION) involve anatomical factors peculiar to the optic nerve. The peripapillary choroid supplies blood to both the nerve head and retrolaminar region of the optic nerve. In the presence of hypotension leading to compensatory mechanisms involving chemical mediators such as angiotensin II, peripapillary choroidal vasoconstriction results in anterior optic nerve ischemia.

Most likely, patients who have visual loss weeks to months following surgery represent cases of spontaneous nonarteritic ION unrelated to the cataract surgery; however, those with visual loss in the immediate postoperative period represent a separate clinical entity. In these patients, the exact pathogenesis remains unclear. Hayreh proposes elevated IOP or fall in blood pressure as the possible mechanism. Others suggest possible structural abnormalities in the optic disc.

Clinical Features and Management

Patients present with diminution of vision in the immediate postoperative period or weeks or months following the surgery. The anterior form of ION is characterised by pale optic disc edema involving all or part of the disc with or without splinter haemorrhages in the acute stage. Gradual atrophic changes develop over approximately two months with resolution of the edema. This contrasts with acute posterior ischemic optic neuropathy, wherein there’s a normal disc and fundus at onset, gradually giving way to disc atrophic changes over the next two months. No successful treatment has been found though the use of pulse steroid therapy in the acute phase has shown some promises.

Most studies cite an occurrence of ION in the fellow eye in 30 to 50 per cent of patients. These series were reported before topical anaesthesia was introduced, and these patients had retrobulbar or general anaesthesia. It is not known whether topical anaesthesia is associated with the same risk.

Outer Retinal Ischaemic Infarction

This is a peculiar syndrome occurring as a complication of cataract extraction. Gass first reported a case in 1982. The syndrome is characterised initially by acute loss of central and paracentral vision, which is usually discovered

on the first postoperative day. Fundus examination in these cases revealed that the posterior pole is stippled by diffuse and patchy whitening of the outer retinal layers. Fluorescein angiography shows normal angiographic retinal and choroidal appearance and circulation time, but a peculiar polygonal pattern of fluorescein staining of the pigment epithelium and outer retina is present in the area of retinal whitening. Later the mottling and whitening of the retina disappears with partial recovery of the central visual field. The optic disc and retinal vascular calibre are maintained. Prolonged elevation of the intraocular pressure sufficient to obstruct choroidal blood flow occurring during the use of intraocular volume-reducing devices before surgery, during phacoemulsification is postulated as the major cause of this complication. No beneficial treatment options are available till now.

Age Related Macular Degeneration and Cataract

Age related macular degeneration (ARMD) is the leading cause of visual morbidity among the elderly population in the west and is speedily catching up as an important problem in India also. The most important determinant in the prevalence of ARMD is age as shown by the Framingham Eye Survey. The prevalence of clinically significant ARMD was 1.6 percent of persons aged 52 to 64, 11.0 percent of persons between the ages of 65 and 74, and 27.9 percent of persons 75 to 85 years showing clearly the importance of age in the development of ARMD. Thus it goes without saying that a lot of elderly patients who have cataract are also likely to have ARMD.

In all cases where the visual loss is not explainable by cataract alone, we should have a detailed examination of the macular area to rule out any changes of ARMD. It is important to keep in mind that there are two important clinical forms of age related macular degeneration : a) Dry age related macular degeneration, which accounts for 90 per cent of patients with this condition, but causes only 10 per cent of the total blindness attributable to this disorder and b) wet (exudative ARMD) which accounts for 105 of the patients, but 90 per cent of the blindness caused by this disorder. Manifestaions of dry ARMD include macular drusen, pigmnetary changes and geographic atrophy. Drusen do not persay result in visual loss. Pigmentary changes and geographic atrophy can result in mild to moderate visual loss. Dry ARMD usually presents with a raised lesion, which may be a serous detachment, retinal pigment epithelial detachment or a disciform subretinal scar. The presence of subretinal blood and/or exudates is a hallmark of exudative age related

macular degeneration. This can result in severe visual loss (less than or equal to 5/200) though the visual acuity may be preserved for a few weeks or months in the early stages of the disease process. Patients with severe age related macular degeneration often give a history of loss of colour perception. The presence of this history in a patient with cataract which is too extensive to permit fundus evaluation should warn the surgeon of the possibility of this disorder. Patients with ARMDshould be explained regarding the disorder and should be kept on regular follow-ups. Preoperative evaluation should include a laser interferometry or potential visual acuity meter for predicting the possible visual outcome. A fluorescein angiography should be obtained preoperatively if the fundus is visible. If it is not visible, then an angiography should be arranged postoperatively.

During surgery, it is possible to give the patient an advantage of magnification by using Gallelian telescopic system. Undercorrection of the IOL power and positive correction given outside will give the patient more magnification than with his correct power of IOL. Such a course may be worthwhile in a patient who is likely to have significant visual defects due to ARMD. A good refraction and low visual aids are to be offered to the patient. Postoperatively the patient should be assessed properly for the ARMD with a fluorescein angiography and should be followed up regularly with an Amsler’s grid.

Distortion on the Amsler’s grid testing is an early indication of development of exudative ARMD in a patient who is previously suffering from the dry form of

the disease. Recent studies have indicated that high doses of anti-oxidants ( Vitamin C 500 mg, vitamin E 400 IU and beta-carotene) along with 80 mg of zinc and 2 micrograms of copper per day can significantly bring down the risk of both moderate and severe visual loss in patients with age related macular degeneration.

Patients who develop the exudative form of the disease would need to be treated by argon laser (If the lesion is greater than 200 micrometer away from the fovea or by Photodynamic therapy or Transpupillary thermotherapy if the lesion is juxta-or subfoveally located. Both these therapies have shown promise for the management of patients with exudative age related macular degeneration involving the fovea. The role of photodynamic therapy with verteporfrin in the management of subfoveal exudative ARMD has been validated by a number of double masked placebo controlled trials. Both Photodynamic therapy and Transpupillary thermotherapy therapies are now available in a number of centres in India.

The conditions described above represent some of the commoner and more important posterior segment disorders that a small incision cataract surgeon is likely to encounter in his practice. Quite obviously, the list is not exhaustive and does not purport to be complete. The objective of the authors was to provide a small incision cataract surgeon with information regarding basic practical approach to management of the more important posterior segment disorders seen in clinical ophthalmic practice.

GlaucomaSICSand 37

P Mishra

S Thanikachalam

Coexistence of cataract and glaucoma in the same eye is frequently encountered in elderly population. The surgeon should consider the option

of performing cataract and glaucoma surgeries in two stages or to combine in one sitting that is more appropriate for the individual depending on the visual status and condition of the eye. Over the past decade combined cataract extraction and glaucoma filtration surgery has been shown to be an effective procedure for the patients having glaucoma with visually significant cataract. Phacotrab, phacoemulsification combined with trabeculectomy is widely acclaimed procedure for these cases, but it is not so popular in the developing countries because of its cost factor and long learning curve. In this chapter we would like to discuss an alternate procedure, non-phaco SICS and trabeculectomy which is very simple to perform (easy learning curve) and cost effective.

The anatomic and physiologic alterations occurring in glaucomatous eyes are protean. Corneal decompensation seen after otherwise uncomplicated cataract extraction is common in-patients having sustained a severe attack of ACG and all attempts to prevent corneal trauma is ensured during cataract surgery. Patients with pseudoexfoliation syndrome have abnormal zonules and capsules, which might predispose to capsular rent, pigment dispersion, break of aqueous barrier, hyphaema etc. The lenses of patients with long-standing glaucoma and advanced cataract often subluxate, if not fully, has to be kept in mind and to be managed more cautiously. So as the atonic pupil that follows after an acute attack of ACG is fixed and dilated requires a large IOL optic to prevent glare and monocular diplopia. Recognizing these factors preoperatively remains the key for the sucessful visual outcome in combined surgery.

Indication

Presence of visually significant cataract with glaucoma is considered for non-phaco SICS trabeculectomy, and other indications are:

1.Inadequate control of IOP

2.Medical intolerance/poor compliance

3.Mild to moderate optic nerve damage

4.Advanced glaucoma.

Instrumentation

•26-G needle

•Hydrodissection cannula

•Crescent knife/ Diamond knife, round type blade with 4 mm long sharp sides

•Angled keratome, 2.65 mm

•Microvectis (micro lens loop)

•Simcoe cannula

•Weckcell sponges

•9-0, 10-0 nylon suture

•Punch forceps or Scleral trephine(1.5, 2 mm).

Surgical Techniques

Anaesthesia

Combined surgery is most safely performed with peribulbar anaesthesia. The anaesthetic solution consists of mixture of 2 per cent lidocaine and 0.5 per cent bupivacaine. It is injected into the anterior orbit by two points technique. The 26-G needle introduced below the supraorbital notch and advanced to a mid orbit depth, the second incision site is given above the inferior orbital rim near lateral canthus.

Conjunctival Flap

There have been conflicting reports regarding the safety and efficacy of the limbus-based vs the fornix-based conjunctival flaps in combined surgery of cataract and glaucoma.1,2 The fornix-based conjunctival flap in this combined procedure has the advantages of better exposure of the surgical site, less handling of the conjunctival flap and more posterior development of the conjunctival filtering bleb. For the above reasons we

Fig. 37.1: Scleral tunnel formation with crescent

always prefer a fornix-based conjunctival flap (Fig. 37.1), which is closed by suturing one or both ends of the flap to the limbus with 9-0 nylon suture for a tight limbal closure. Sometimes watertight closure is achieved by suturing the flap with peripheral cornea with 10-0 nylon. The conjunctival flap is usually dissected in the superior quadrant and the width of the conjunctival dissection should be slightly larger than anticipated scleral tunnel incision for better exposure. The conjunctival reflection should be made as posterior as possible, at least 8-10 mm posterior to the limbus. Haemostasis of episcleral blood vessels is achieved by bipolar diathermy.

Scleral Incision

A three-stage (triplanar) scleral tunnel incision is made with the initial external frown incision given approximately 2-3 mm posterior to the limbus. It is given either with a diamond knife or a stainless steel blade. The second incision is intrascleral dissection (Fig. 37.1) and the third oblique entry into anterior chamber through clear cornea. The scleral dissection is kept half the thickness and the anterior entry wound should not extend too anterior else it will cause striae formation in the posterior cornea, which prevents adequate visualisation of the anterior segment. A low molecular viscoelastic substance is injected to reform the anterior chamber once its entry is made with angled micro-keratome. From one end of the incision another radial incision is given which is extended to the limbus (Fig. 37.2). This step is essential for trabeculectomy, which may be given after completion of the cataract surgery and lens implantation.

Capsulorhexis

Continuous curvilinear capsulorhexis is performed using 26G needle or rhexis forceps. The size of capsulorhexis

Fig. 37.2: Frown incision and a radial incision at one end for trabeculectomy

is often limited by small pupil or poor dilation in glaucoma patients on long-standing medical therapy. Inability to dilate pupil sufficiently or small rhexis may cause vitreous loss due to zonular dialysis during nucleus management. All necessary steps to be undertaken for management of small pupil. When necessary, multiple partial sphincterotomies or stretching of pupil with Sinskey hook may be done to enlarge the pupil. Rhexis can be performed very easily in mature/advanced cataracts by using Trypan blue, which enhances the visualisation by staining the anterior capsule. Whenever the rhexis is small, two relaxing incisions at 2 and 10 O’clock are usually required to luxate the nucleus easily in to anterior chamber in nuclear cataracts.

Hydrodissection

It is a crucial step to be performed in all the cases, which separates the nucleus from its capsular attachments. The anterior capsule is elevated with a 26 G cannula attached to a 2 ml syringe filled with BSS and the fluid is injected slowly and continuously beneath the edge of capsulorhexis to create a fluid wave that passes across the red reflex. The fluid wave is not visible in dense cataracts. In such cases, when hydrodissection is completed, the nucleus appears to move forward following which it must rotate freely inside the capsular bag.

Nucleus Management

Nucleus delivery with conventional large incision surgery is dangerous in uncontrolled glaucoma, because of the positive vitreous pressure. The small incision technique

offers distinct advantage over it with safe removal of the nucleus. The nucleus is luxated into the anterior chamber with Sinskey hook or bent 26-G needle. This is usually done by rotating the nucleus either clockwise, anticlockwise or both following reforming the anterior chamber with viscoelastics. Once it is in the anterior chamber the nucleus is gently expressed through the scleral tunnel using a microvectis. This is our preferred technique for nucleus removal over the last 5 years. The residual cortex is aspirated with Simcoe cannula. Complete cortical removal, with sclerostomy site free of capsule, cortex, blood or vitreous is extremely important for the success of combined surgery. The posterior capsule may be polished, if necessary. The viscoelastics is placed in the capsular bag to distend sufficiently enough for lens implantation. IOL implantation is performed by using any preferred technique. Pupil is restored to round and small size by gently stroking the iris, even intracameral pilocarpine can be used for intraoperative miosis, which should be thoroughly washed away from the anterior chamber.

Antimetabolites

If antimetabolites are used for intractable glaucoma it should be applied under the conjunctival/scleral flap. It is useful in high-risk cases where chances of failure of trabeculectomy are high; it may effectively limit fibrosis, scarring and bleb failure. MMC offers a beneficial effect on combined filtration surgery without having the corneal toxicity of 5 FU.5,6 Excess concentration of the drug may cause conjunctival necrosis with underlying scleral melting, bleb leak, hypotony and even endophthalmitis. The preferred method is, a 5× 5 mm sponge soaked in mitomycin C with a concentration of 0.25 mg/ml is applied to the filtered area for about two minutes with the conjunctiva and tenons draped over it. Care was taken to avoid contact between the sponge and the edge of the flap by holding conjunctiaval flap edge away from the sponge with tying forceps.6,7 The site is then irrigated with BSS to remove residual drug.

Scleral Flap

Dissection of scleral flap (Fig. 37.1) is vital step for successful wound closure. If scleral flap is too thin it will lead to button holing or tear formation resulting in excessive filtration with postoperative hypotony and the situation is made even worse with use of MMC. If the flap is made too thick it may lead to premature entry into the anterior chamber with subsequent iris prolapse. The ideal dissec-

tion that is sufficient for good flap is about half the thickness of sclera. Once IOL implantation is over anterior chamber is reformed with either air (Fig. 37.3) or viscoelastics, another radial incision from one end of scleral groove (frown incision) is given upto the limbus (Fig. 37.2). A triangular flap is fashioned (Fig. 37.4); it should be handled with fine forceps to avoid injury to it. The dissection is continued anteriorly into the cornea so that scleral spur can be identified through deep scleral lamella and 1 mm of cornea anterior to the spur is seen. When the scleral flap is retracted towards the pupil by the assistant a blade breaker knife or Bard Parker knife with 11-G blade is used to make two radial (Fig. 37.5) incisions about 1.5 mm apart extending for about 2 mm from corneolimbal junction to the sclerolimbal. A third incision is made parallel to the limbus at the corneolimbal junction. The free edge of block tissue is grasped with Pierse Hoskins forceps and rotated posteriorly allowing the angled vannas scissors to cut horizontally at the scleral spur.

Fig. 37.3: IOL implanted with air bubble in AC

Fig. 37.4: Dissection of triangular flap at one end of frown incision

Fig. 37.5: Radial incision over the trabecular meshwork

Alternatively Kelly punch is used to excise trabecular tissue; the third option is, to use 1.5 or 2 mm scleral trephine to remove a circular piece of trabecular meshwork to create filtration fistula. The block of tissue removed (Fig. 37.6) should contain anterior scleral spur, Schlemm’s canal, trabecular meshwork, Schwalbe’s line and peripheral cornea. A peripheral iridectomy (Fig. 37.7) is performed and the anterior chamber reformed with BSS. The scleral flap is closed with single 9-0 nylon suture at the apex of the flap, where the radial incision was initiated.

Conjunctival Closure

The fornix based conjunctival flap is closed by suturing its one or both ends to the limbus with 9-0 nylon suture for a tight limbal closure. Some times the conjunctival wound is closed with peripheral cornea by running 10-0 nylon suture for a watertight closure.8 The anterior chamber is filled with air for wound stability (Fig. 37.8).

Fig. 37.7: Deep scleral flap visible, iridectomy done

Fig. 37.8: Conjunctiva is closed

Postoperative Medications

Topical corticosteroids are administered generously in the immediate postoperative period to inhibit inflammation and to decrease scar tissue, which is tapered slowly within 2-3 weeks. Cyclopentolate (1%) is used whenever there is severe iritis for few days. Digital massage over cornea through the lids is applied whenever necessary during early postoperative period, particularly when the IOP is greater than 20 mm Hg8. Drugs that decrease secretion of aqueous, acetazolamide should not be used unless indicated. Persistent flat anterior chamber in the postoperative period should be diagnosed by Siedel’s test and managed accordingly.

Conclusions

same site. The procedure employing non-phaco scleral tunnel small incision surgery for cataract extraction also provides access for filtration surgery simultaneously with improved success and safety without the need for second surgical procedure. It does not require longec learning curve, greater skill, and at the same time gives fairly excellent results. No doubt, this can be considered as a low cost alternative to phacotrabeculectomy in the developing countries.

REFERENCES

1.Mc Cartney DL, Memmen JE, Stark WJ et al: The efficacy and safety of combined trabeculectomy, cataract extraction and intraocular lens implantation. Ophthalmology 95: 75463, 1988.

2.Simmons ST, Litoff D, Nichols DA et al: Extracapsular cataract extraction and posterior chamber intraocular lens

implantation combined with trabeculectomy in patients with glaucoma. Am J Ophthalmol 104: 465-70, 1987.

3.Hurvitz LM: Combined surgery for cataract and glaucoma.

Curr Opinions Ophthalmol 4(2): 73, 1993.

4.Lyle WA, Jin JC: Comparison of a 3 and 6 mm incision in combined phacoemulsification and trabeculectomy. Am J Ophthalmol 111: 189-96, 1991.

5.Costa VP, Moster MR, Wilson RP et al: Effects of topical mitomycin C on primary trabeculectomies and combined procedures. Br J Ophthalmol 77: 693, 1993.

6.Wong P, Goldenfeld M, Ruderman J et al: 5 Flurouracil (5FU) after primary combined filteration surgery: A prospective, randomised study. Invest ophthalmol Vis Sci 34: 727, 1993.

7.Wyse T, Meyer M, Ruderman JM et al: Combined trabeculectomy and phacoemulsification: A one site vs two site approach. Am J Ophthalmol 125(3): 334-39, 1988.

8.Lemon LC, Shin DH, Kim C et al: Limbus based vs fornix based conjunctival flap in combined Glaucoma and cataract surgery with adjunctive mitomycin C. Am J Ophthalmol 125(3): 340, 1998.

The whole question of a large, medium, small and mini incisions is concerned with the removal of the harder part of the cataractthe nucleus. The

rest can be removed by irrigation/aspiration. In most of the paediatric patients, the size and the hardness of the nucleus permit the performance of the lens removal and intraocular lens implantation manoeuvres through a relatively small incision. However, the presentation of the paediatric patients shows a great variation and the response of the ocular tissues during and after the surgery are different from the adults. The surgical approach to the lens removal and the type of lens implantation is extremely varied and full of controversies.

The purpose of small incision surgery in paediatric patients.

In the adults, the main purpose of a small incision surgery is to minimise postoperative astigmatism. In the paediatric cases, it is to ensure greater safety during the conduct of the surgery and to minimise operative and postoperative problems peculiar to this group. Keeping the incision line suture less is not mandatory.

Clinical situations requiring cataract and implant surgery:

1.Congenital cataract.

2.Dislocated lens.

3.Traumatic cataract.

4.Secondary cataract.

5.Secondary lens implantation.

Congenital Cataract

There are more varieties of congenital cataract (Fig. 38.1) than meet the eye or are described in the literature. From the surgical point of view, the following observations are important:

1.The integrity of the capsular bag About 10 per cent of congenital cataracts have a pre-existing rent/ opening/dehiscence/absence of the posterior capsule in a small or a large area of the posterior capsule.

Fig. 38.1: Congenital cataract

2.The physical state of the cataractous lens The consistency of the cataract may vary to milky fluid like to hard rock like, with all the intermediate stages.

3.The anterior capsule Since an extracapsular surgery

is being performed, an important component of success is formed by excellence obtained in the capsulotomy step. The anterior capsule varies in many characters like its consistency, uniformity, fragility, support from the underlying cortex and the pull of the zonular fibres.

Surgical approach to congenital cataract:

Only Lens Extraction

The lens may be removed through:

a.Small limbal incision/incisions.

b.Pars plana lensectomy. In my opinion a pars plana approach is riskier, since it unnecessarily cuts through important vitreous cisterns, produces fibrotic reactions, and is likely to cause some vitreous-lens mix. A number of vitreoretinal problems can arise as a result.

c.The anterior route: This is the one described below.

The Anterior Route Approach to

Congenital Cataract

If an intraocular lens implantation is desired, then the minimum size of the incision shall take in to consideration the widest diameter of the intraocular lens optic. My approach is described below which can be modified to suit the needs of an individual surgeon.

Incisions

a.Two side port pocket incisions 1 mm wide, 180 degrees apart. The pocket depth may be kept at about 1 mm. First a 0.3 mm deep vertical groove is made, which is followed by horizontal pocket section.

b.The anterior chamber is filled with a visco-elastic material, like HPMC. The eye should feel firm at this point which will help the next step.

c.A 4.25 mm wide vertical groove is made at the upper limbus. This is followed by the making of a pocket section, the depth being about 2 mm.

The incisions are best made with diamond knives. However, good quality disposable steel blades are

also available for the purpose.

The purpose of making pocket incisions is manifold. They help to maintain the depth of the anterior chamber during surgery. They minimise the tendency of the iris to prolapse through incisions. They prevent the formation of peripheral anterior synechiae. The anterior chamber should be kept deep throughout the procedure either by irrigation or by keeping HPMC in it. A flat anterior chamber invites the formation of fibrin during the surgery, which can be quite troublesome. The younger the patient, the greater is the need to take observe this precaution. Lastly, if and when suturing is necessary, it can be done easily.

d.The anterior chamber is once again filled with HPMC.

Anterior Capsulotomy

Anterior capsulectomy /capsulotomy is an important step. The following types of anterior capsulectomies are possible:

•CCC This is done with a capsulotomy needle through the side port alone or assisted by a forceps through the upper larger incision. The anterior capsule in the paediatric patients is sometimes so elastic that the capsulotomy can run into the periphery. This spoils the ground for in the bag implantation, if so planned.

•Can opener capsulotomy of a very large size can be done with a view to destroy most if not all the anterior capsule cells. However, the equatorial cells still remain.

A subtotal anterior capsulectomy makes it very easy to remove the cortex from the fornices.

•Kloti needle This bipolar cautery needle gives more control on the size and shape of anterior capsulotomy. It takes about 30 to 40 seconds to perform a good capsulectomy. The capsule seems to stick to the needle as it is cut.

•Fugo blade The blade tip is in the form of a 100 micron filament, which when activated gets covered with a 30 micron wide column of plasma. The plasma has great cutting properties. It cuts without any resistance. A capsulotomy can be performed in 5 to 10 seconds. It may be performed in parts, which are then united by retouching. The cut edge made with plasma energy becomes strong and resists tearing, something that does not happen with other capsulotomies. Fugo blade capsulotomy is done in a deep anterior chamber.

Cataract Removal

The cataract removal in uncomplicated cases have soft consistency cortex and nucleus can be performed in the following way:

•Irrigation/aspiration with any of the well known cannulas. My preference for my own design (made by Indo-German) is due to the fact in this cannula, the irrigation port is on the under surface and the aspirating port is on the anterior surface. With the irrigation on, one can not tear the posterior capsule, since the capsule is pushed away by the fluid pressure. The irrigating fluid gets into the fornices and pushes out the cortical matter, making it easy to attract it to the aspirating port. The aspiration is done with a 1 ml disposable syringe. The removal of the cortex under the pocket incision is difficult. For this reason the 12 O’ clock cortex is loosened by irrigation from the side port incisions.

•Irrigation/aspiration with the help of phaco or nonphaco irrigation/aspiration machines. The procedure is quicker, since the fluid movement is fast and aspiration can be done at a higher vacuum pressure.

•“Dry aspiration”: Little or no saline is used in this technique. A 22-gauge cannula attached to the syringe is used to suck out the lens. Each aspiration is followed by injecting HPMC in the bag to loosen more of the lens. Care is taken not to aspirate near the posterior capsule, so as not to produce a tear.

I do dry aspiration as follows. From the side port incisions and from the top, I inject HPMC under the cut edge of the anterior capsule. As the lens matter rises, I