Ординатура / Офтальмология / Английские материалы / Comprehensive Ophthalmology_Khurana_2007

3. Tenotomy scissors or strabismus scissors (Fig. 24.40). They are plain straight or curved scissors with blunt ends. Uses: (i) To cut the extraocular muscles during squint surgery and enucleation operation. (ii) To separate the delicate tissues without damaging the surrounding area in oculoplastic operations and squint surgery.

Fig. 24.40

4. Corneal scissors or section enlarging scissors

(Fig. 24.41 A & B). They are fine curved scissors. Their cutting blades are kept apart by spring action. They are available in various shapes and sizes. The universal corneal scissors can be used for both sides while right and left curved corneal scissors are separated for the two sides. Uses: (i) These are used to enlarge corneal or corneoscleral incision for conventional intracapsular and extracapsular cataract extraction (sparingly performed procedures now-a- day) cataract surgery. (ii) To enlarge corneal incision in keratoplasty operation. (iii) To cut the scleral and trabecular tissue in trabeculectomy.

Fig. 24.41A

Fig. 24.41B

5. de Wecker’s scissors (Fig. 24.42). They are fine scissors with small blades directed at right angles to the arms. The blades are kept apart, making V-shape, by spring action. Uses: It is used to perform iridectomy, iridotomy and to cut the prolapsed formed vitreous and pupillary membrane.

Fig. 24.42

6. Spring scissors (Westcott’s) (Fig. 24.43). They are stout scissors available with straight or curved blades with sharp or blunt tips. The blades are kept apart by spring action. Uses: They are used as a handy alternative to plain straight and plain curved ringed scissors for cutting and undermining conjunctiva in various operations and to cut sutures.

Fig. 24.43

7. Vannas scissors (Fig. 24.44). These are very fine delicate scissors with small cutting blades kept apart by spring action. The blades may be straight or curved. Uses: (i) These are used for cutting anterior capsule of the lens in extracapsular surgery and for cutting 10-0 nylon sutures. (ii) For cutting inner scleral flap in trabeculectomy. (iii) For doing pupillary sphincterotomy. (iv) For performing iridectomy. (v) For cutting pupillary membrane.

Fig. 24.44

8. Enucleation scissors (Fig. 24.45). They are large, stout and strong scissors having curved sharp blades with blunt ends. Uses: They are used to cut the optic nerve during enucleation operation.

Fig. 24.45

VII. Clamps

1. Lid clamp or entropion clamp (Fig. 24.46). It consists of a D-shaped plate opposed by a U-shaped

rim, which when tightened with the help of a screw, clamps the tissues. Two clamps are required; one can be used for right upper and left lower lid and the second for right lower and left upper lid. While applying the lid clamp, the plate is kept towards the conjunctival side, the rim on the skin side, and the handle is always situated on the temporal side.

Advantage over lid spatula: It is a self-retaining instrument and does not need an assistant to hold. Disadvantages: (i) Operative field is less. (ii) Pressure necrosis can occur if fitted tightly. Uses: It is used in lid surgery e.g., entropion, and ectropion corrections. It protects the eyeball, supports the lid tissue and provides haemostasis during surgery.

Fig. 24.46

2. Chalazion clamp (Fig. 24.47). It consists of two limbs like forceps, which can be clamped with the help of a screw. The tip of one limb is flattened in the form of round disc while the tip of the other arm has a small circular ring. Usually the flat disc is applied on the skin side and ring on the conjunctival side of the chalazion. Uses: To fix the chalazion and achieve haemostasis during incision and curettage.

Fig. 24.47

3. Ptosis clamp (Fig. 24.48). It is like forceps with J- shaped ends having internal serrations. The clamp has a locking mechanism. Use: To hold levator palpebrae superioris muscle during ptosis surgery.

Fig. 24.48

VIII. Additional instruments for cataract surgery

1. Lens spatula (Fig. 24.49). It is a flat metallic handle with tiny spoon-shaped ends. It is used to apply counter-pressure at 12 O’clock position during extraction of lens in Smith’s technique and expression of nucleus in extracapsular cataract extraction.

Fig. 24.49

2. Wire vectis (Fig. 24.50). It is wire loop attached to a metallic handle. Uses: It is used to remove dislocated or subluxated lens. and nucleus in ECCE.

Fig. 24.50

3. Irrigating wire vectis (Fig. 24.51). Is is a modified vectis in which the loop is made of a thick hollow wire. The anterior end of the loop has three 0.3-mm openings. The posterior end of the loop is continuous with a hollow handle. The posterior end of the hollow handle has a hub similar to that of a hypodermic needle to which is attached a syringe or infusion set. The size of the loop of the vectis is variable. In commonly used wire vectis the loop is 4 mm in width and about 8-9 mm in length. The superior surface of the loop has a slight concavity to accommodate the lens nucleus. Uses. Irrigating wire vectis is most commonly used to deliver nucleus in manual small incision cataract surgery (SICS) and in conventional ECCE by hydroexpression or viscoexpression technique.

Fig. 24.51

4. Two-way irrigation and aspiration cannula (Fig.

24.52). It is available in various designs, commonly used are Simcoe’s classical or reverse cannula. Uses:

(i) For irrigation and suction of the lens matter in extracapsular cataract extraction. (ii) Aspiration of hyphaema.

Fig. 24.52

5. Iris repositor (Fig. 24.53). It consists of a delicate, flat, malleable, straight or bent blade with blunt edges and tip attached to a handle. Uses: (i) To reposit the iris in the anterior chamber in any intraocular surgery. (ii) To break synechiae at the pupillary margin.

Fig. 24.53

IX. Additional instruments for intraocular lens implantation

For IOL implantation, the cataract surgery set should contain the following basic additional instruments: 1. IOL holding forceps (Fig. 24.54). It is a springaction forceps with short, blunt and curved blades having smooth edges and tips with plateform (no teeth or serrations). Use: To hold optic of non-foldable PMMA IOL during implantation.

Fig. 24. 54

2. Kelman-McPherson forceps (Fig. 24.55). These are fine forceps with bent limbs. Uses: (i)To hold the superior haptic of IOL during its placement. (ii) To tear off the anterior capsular flap in ECCE. (iii) Can be used for suture tying.

3. Sinskey hook or IOL dialer (Fig. 24.56). It is a fine but stout instrument with a bent tip. The tip engages the dialing holes of the IOL. Uses: (i) It is used to dial the PMMA non-foldable IOL for proper positioning in the capsular bag or ciliary sulcus. (ii) It can also be used to manipulate the nucleus in phacoemulsification surgery. Nucleus mani-pulation may be in the form of nucleus rotation in the capsular bag, cracking of the nucleus and feeding of the nuclear fragments into the phaco tip.

Fig. 24.56

4. Hydrodissection cannula (Fig. 24.57). It is a single bore 25G, 27G or 30 G cannula wih a 45° angulation at about 10 to 12 mm from the free end. The tip at the free end can be flattened or bevelled. Uses. It is used to perform hydrodissection (separation of posterior capsule from the cortex and hydrodelineation (separation of cortex from the nucleus) in phacoemulsification and manual SICS. This cannula is attached to the syringe carrying irrigating fluid. For hydrodissection its tip is introduced beneath the anterior capsular margin after capsulorhexsis and fluid is injected to obtain subcapsular dissection.

Fig. 24.57

5. Chopper (Fig. 24.58). The chopper is a fine instrument resembling sinskey hook in shape. The inner edge of the bent tip is cutting and may have different angles. Uses. It is used to split or chop the nucleus into smaller pieces and also for nuclear manipulation in phacoemulsification surgery.

6. Ring capsule polisher or posterior capsule polishing curette (Fig. 24.59). It consists of a long handle and a bent slender neck. The tip of the instrument has a tiny circular ring. Uses. It is used to clear and polish the posterior lens capsule to make it more clear in the extracapsular cataract surgery. It is specially used when a plaque or sticky cortex is adhered to the posterior capsule.

Fig. 24.59

X. Additional instruments for glaucoma surgery

1. Scleral punch (Fig. 24.60). It is of the shape of corneal scissors with spring action mechanism. Its one blade is sharp and thick which presses into the second blade which is a hollow rectangular frame. Use: To perform punch sclerectomy during glaucoma surgery.

Fig. 24.60

2. Kelley’s punch (Fig. 24.61). It is used to enlarge the bony opening during DCR operation by punching the bone from margins of the opening. Carelessness during this step can cause accidental damage to the nasal mucosa and the nasal septum. Uses. It is used to perform punch sclerectomy in conventional as well as sutureless trabeculectomy operation.

Fig. 24.61

XI. Additional instruments for lid surgery

1. Chalazion scoop (Fig. 24.62). It has a small cup with sharp margins attached to a narrow handle. Use: To scoop out contents of the chalazion during incision and curettage.

Fig. 24.62

2. Lid spatula (Fig. 24.63). It is a simple metal plate having slightly convex surfaces at either end. Uses: To protect the globe and support the lid during entropion, ectropion, ptosis and other lid surgeries.

Fig. 24.63

XII. Additional instruments for lacrimal sac surgery (DCT and DCR)

1. Punctum dilator (Nettleship’s) (Fig. 24.64). It has a cylindrical corrugated metal handle with a conical pointed tip. Uses: To dilate the punctum and canaliculus during syringing, probing, dacryocystography, DCT and DCR procedures.

Fig. 24.64

2. Lacrimal probes (Bowman’s) (Fig. 24.65). These are a set of straight metal wires of varying thickness (size 0-8) with blunt rounded ends and flattened central platform. Uses: (i) To probe nasolacrimal duct in congenital blockage. (ii). To identify the lacrimal sac during DCT and DCR operations.

Fig. 24.65

3. Lacrimal cannula (Fig. 24.66). It is a long curved hypodermic needle with blunt tip. Uses: (i) For syringing the lacrimal passages. (ii) As AC cannula for putting air or balanced salt solution in the anterior chamber during intraocular surgery.

Fig. 24.66

4. Bone punch (Fig. 24.67). It consists of a stout spring handle and two blades attached at right angle. The upper blade has a small hole with a sharp cutting edge. The lower blade has a cup-like depression. Uses: It is used to enlarge the bony opening during DCR

operation by punching the bone from margins of the opening. Carelessness during this step can cause accidental damage to the nasal mucosa and the nasal septum.

Fig. 24.71

XIII. Additional instruments for enucleation and evisceration

1. Optic nerve guide (enucleation spoon) (Fig. 24.72). It is a spoon-shaped instrument with a central cleavage. Use: To engage the optic nerve during enucleation.

Fig. 24.67

5. Chisel (Fig. 24.68). It consists of a blade having a sharp-cutting straight edge with one surface bevelled. It has a long and stout handle. Use: To cut the bone during DCR and orbitotomy operations.

Fig. 24.68

6. Hammer (Fig. 24.69). It is a small steel hammer attached to a corrugated handle. Use: To hammer the chisel during DCR and orbitotomy operations.

Fig. 24.72

2. Evisceration spatula (Fig. 24.73). It consists of a small but stout rectangular blade with slightly convex surface and blunt edges attached to a handle. Use: To separate out the uveal tissue from the sclera during evisceration operation.

Fig. 24.73

3. Evisceration curette (Fig. 24.74). It consists of an oval or rounded shallow cup with blunt margins attached to a stout handle. Use: To curette out the intraocular contents during evisceration operation.

Fig. 24.69

7. Lacrimal sac dissector and curette (Fig. 24.70). It is a cylindrical instrument, one end of which is a blunttipped dissector and the other end is curetted. Use: In lacrimal sac surgery.

Fig. 24.70

8. Bone gouge (Fig. 24.71). It consists of a stout metallic handle, one end of which is longitudinally scooped. The edges of the scoop are sharp. Use: To smoothen the irregularly cut margins of the bone by nibbling small projecting bone and in DCR operation and in orbitotomy operation.

Fig. 24.74

STERILIZATION, DISINFECTION

AND FUMIGATION

STERILIZATION AND DISINFECTION

It is a process which kills or removes all microorganisms including bacterial spores from an article, surface or medium. It must be differentiated from disinfection which destroys pathogenic microorganisms but does not kill or remove spores.

Sterilization can be accomplished by physical agents (viz. sunlight, heat, filtration and radiation) and chemical agents (such as alcohols, aldehydes, halogens, phenol, surface acting agents and gases).

Methods

(A) Heat sterilization

Both dry and moist heat can be used.

Dry heat sterilization methods

1.Flaming. It can be used to sterilize points of forceps, hypodermic needles, tips of AC cannula and scraping spatulas. The instrument is held in a bunsen flame till it becomes red hot.

2.Incineration. It is used to destroy soiled dressings, beddings and pathological materials.

3.Hot air oven. It is the most commonly used method of sterilization by dry heat. It kills bacteria, spores and viruses. This method is employed to sterilize instruments like forceps, scissors, scalpels, glass syringes, glassware etc. The item must be double wrapped and kept at 150° C for 2 hours.

Moist heat sterilization methods

1.Boiling. It kills bacteria and viruses. Heavier metallic ophthalmic instruments, e.g., Bard-Parker handles, lid guards etc. can be sterilized by boiling in water for 30 minutes. This method, however, blunts the cutting instruments.

2.Steaming. It kills most bacteria and viruses, but not spores. The instruments are placed on a shelf above the level of water and steamed for about 30 minutes. Most of the metallic instruments e.g., scissors and knives can be sterilized by this method.

3.Autoclaving (steam under pressure).It is the most widely used method for sterilization. It is based on the principle that at boiling point of water, the vapour pressure equates the atmospheric pressure. So, if the pressure is increased, boiling point tends to rise, which increases the penetrating power of the steam.

Autoclaving at 121° C under 15 1b/in2 pressure for 20 min. or at 116° C under 10 1b/in2 pressure for 40 min. kills bacteria, spores and viruses. This method is suitable for sterilizing various instruments, linen, glass wares, rubber goods, gowns, towels, gloves dressings and eyedrops.

(B) Chemical sterilization

1.Savlon. It comprises of cetavlon or cetrimide and chlorhexidine. Cetavlon is a surface active agent and chlorhexidine is a phenol. It is active against most gram-positive organisms. It is used for cleaning/preparation of skin. Scissors, catheters, knives etc. may also be sterilized with it.

2.Spirit (95% alcohol). It kills bacteria and spores, but not viruses. It is mostly used with savlon.

3.Methylated spirit. It is 70 percent isopropyl alcohol. Schiotz tonometer can be sterilized by it.

4.Formaldehyde

i.Formalin. 10 percent solution of formalin has a marked bactericidal, sporicidal and some viricidal activity. It is suitable for cryoextractor probes and heat sensitive instruments.

ii.Formaldehyde gas. It may be used for fumigating wards, sick rooms and laboratories. But this gas is irritant and toxic when inhaled.

5.Glutaraldehyde (2%). It is available as ‘Cidex’ solution. It has a special activity against tubercle bacilli, fungi and viruses. It is mostly used for sterilising endoscopes because it has no damaging effect on the lenses. It can be safely used for catheters, face-masks, anaesthetic tubes and metal instruments. However, it is not suitable for silicone tubing. It is specially used to sterilize sharp instruments, as it does not affect the sharpness. In three hours, the instruments are free of pathogens and spores. Instruments should be thoroughly washed with sterile distilled water before use.

6.Hydrogen peroxide. A 3 percent solution of

H2O2 is used for sterilisation of applanation tonometers, prisms and ophthalmoscopy lenses. It is specially active against AIDS and herpes viruses.

7.Ethylene oxide gas: It is a highly inflammable gas and is usually mixed with an inert gas like nitrogen or carbon dioxide. It denatures the protein molecules. It is effective against almost all bacteria, spores and viruses. Goniotomy lenses, indirect ophthalmoscopy lenses, DCR tubings and cryoprobes can be sterilized with it.

8.Acetone. Use of acetone is a quick and cheap method of sterilising instruments. Instruments should be kept in acetone for 5 minutes and then thoroughly washed with sterile water before use.

(C) Radiation sterilization

1.Ionising radiations: These include X-rays, gamma-rays, cosmic rays. They are highly lethal to DNA and thus kill all types of micro-organisms. They can penetrate solids and liquids without raising the temperature appreciably (cold sterilisation). They are used for sterilizing plastic syringes, swabs, catheters, tubings etc.

2.Non-ionising radiations: They act as a form of hot air sterilization since they are absorbed as heat. They include the infrared rays which is used for rapid mass sterilization of disposable syringes.

Fumigation of operation theatre

Fumigation refers to disinfection of the operating room by exposure to the fumes of a vaporised disinfectant. Formaldehyde is an effective agent commonly used to sterilize the operating room. For optimum disinfection, formaldehyde fumigation is recommended fortnightly as a routine and at the end of an operating session of a grossly infected case.

Method of fumigation involves following steps:

Cleaning and scrubing of the operating room is done thoroughly and the floor is carbolised.

Sealing of all the aperatures in the room is done prior to fumigation leaving only one door open.

Generation of formaldehyde is done by addition

of 150gm of potassium permanganate (KMnO4 ) to 280ml of formalin in a steel bucket for every 1000 cubic feet of room volume. Alternatively, 500 ml of 40% formaldehyde in one litre of water is put into an electric boiler or a large bowl placed on a electric hot plate with safety cut-out when boiling dry.

Closure and sealing of the door is done quickly. After formaldehyde vapour is generated the room should be left closed for 24 to 48 hours.

Neutralization of formaldehyde is then carried out with ammonium solution left in the operating room for a few hours. One litre of ammonium solution plus one litre of water is required to neutralize every litre of 40% formaldehyde used.

Replacement of left out formalin with air.

Subsequently the room doors may be opened for a short period or the air-conditioning switched on to replace the formalin with air.

RELATED QUESTIONS

ANAESTHESIA FOR OCULAR SURGERY

How topical ocular anaesthesia is achieved? What

are its indications?

Topical ocular anaesthesia is achieved by instillation of 2 to 4% xylocaine or 1% amethocaine, 4 times every 4 minute.

Indications

For minor procedures like removal of corneal foreign body, removal of stitches etc.

Along with retrobulbar block.

Recently, phacoemulsification operation is being done under topical anaesthesia.

What are various techniques of facial block anaesthesia?

Van Lint’s block: Terminal branches of facial nerve are blocked by injecting 2.5 ml of anaesthetic solution in deeper tissues just above the eyebrows and just below the inferior orbital margin.

O’Brien’s block: Facial nerve is blocked at the neck of mandible

Nadbath blcok: Facial nerve is blocked near the stylomastoid foramen.

Atkinson’s block: Only superior branches of facial nerve are blocked by an injection at the inferior margin of zygomatic bone.

Where injection is made for retrobulbar block?

For a retrobulbar block, 2 ml of 2% xylocaine is injected into the muscle cone.

What are the effects of retrobulbar block ?

Ciliary nerve and ciliary ganglion block

Ocular akinesia

Ocular anaesthesia and analgesia

Dilatation of the pupil

Ocular hypotony

Enumerate complications of retrobulbar block.

Retrobulbar haemorrhage

Globe perforation

Optic nerve injury

Extraocular muscle palsies

What is the technique of peribulbar block?

An anaesthetic solution, 6 to 9 ml (a mixture of 2% xylocaine and 0.5-0.75% bupivacaine) in a ratio of 2:1 with hyaluronidase 5 I.U./ml with or without adrenaline 1:1 lac is injected into the peripheral orbital space.

What are the advantages of peribulbar block?

No separate facial block is required.

Complications associated with retrobulbar block are almost eliminated.

OPHTHALMIC INSTRUMENTS AND EYE OPERATIONS

Usually a student is asked to describe a particular ophthalmic instrument in reference to following aspects:

Identification of the instrument

Methods of its sterilization

Uses of the instrument

OPERATIONS FOR CATARACT EXTRACTION

Name the instruments required for intracapsular

cataract extraction.

The instruments required for intracapsular cataract extraction include superior rectus holding forceps, Stevens’ needle holder, artery forceps, plane forceps, curved ringed scissors, heat cautery or wet-field cautery, razor–blade fragment holder, corneo scleral suturing forceps, corneoscleral section enlarging scissors, iris forceps, deWecker’s iridectomy scissors, lens spatula, lens hook, anterior chamber cannula, iris repositor, spring action fine needle holder.

These instruments form the basic intraocular surgery set.

Name the additional instruments required for

extracapsular cataract extraction.

Cystitome, Vannas’ scissors, McPherson’s forceps, two-way irrigation-aspiration cannula; posterior capsule polisher.

Name (pick up) the additional instruments required

for an intraocular lens implantation.

Anterior chamber cannula for injecting viscoelastic substance, intraocular lens (implant) holding forceps and intraocular lens dialer.

Name the two main techniques of cataract extraction.

1.Intracapsular cataract extraction (ICCE)

2.Extracapsular cataract extraction (ECCE).

What are the advantages of ECCE over ICCE?

1.Extracapsular cataract extraction is a universal operation and can be performed at all ages, except when zonules are not intact. While ICCE cannot be performed below 40 years of age.

2.Posterior chamber IOL can be implanted after ECCE, while it cannot be implanted after ICCE.

3.Postoperative vitreous-related problems (such as herniation in anterior chamber, pupillary block and vitreous touch syndrome) associated with ICCE are not seen after ECCE.

4.Incidence of postoperative complications such as endophthalmitis, cystoid macular oedema and retinal detachment is much less after ECCE as compared to that after ICCE.

What are the advantages of ICCE over ECCE?

1.The technique of ICCE as compared to ECCE is simple, cheap, easy and does not need sophisticated microinstruments.

2.Postoperative opacification of posterior capsule is seen in a significant number of cases after ECCE. No such problem is there after ICCE.

3.ICCE is less time consuming and hence more useful than ECCE for mass scale operations in eyecamps.

Name the methods of lens delivery in intracapsular cataract extraction.

1.Indian Smith method

2.Cryoextraction

3.Capsule forceps method

4.Irisophake method

5.Wire-vectis method for subluxated lens

Name the different techniques of extracapsular catract extraction.

1.Discission or needling

2.Linear extraction or curette evacuation

3.Modern extracapsular cataract extraction (ECCE)

4.Lensectomy

5.Phacoemulsification

What are the main steps of lens removal in ECCE operation ?

1.Anterior capsulotomy

2.Removal of nucleus

3.Aspiration of the cortical lens matter

Name the techniques of anterior capsulotomy

1.Can-opener technique

2.Linear capsulotomy (envelope technique)

3.Continuous circular capsulorhexis (CCC)

What is phacoemulsification ?

Phacoemulsification is a technique of extracapsular cataract extraction in which after the removal of anterior capsule (by capsulorhexis), the lens nucleus is emulsified and aspirated by the probe of a phacoemulsification machine.

What are the advantages of phacoemulsification over the conventional ECCE operation?

1.Corneoscleral incision required is very small (3 mm). Therefore, sutureless surgery is possible with a self-sealing scleral tunnel incision

2.Early visual rehabilitation of the patient

3.Very less astigmatism

What are the main types of intraocular lenses

(IOL)?

The major classes of IOL based on the method of fixation in the eye are as follows:

1.Anterior chamber IOL, e.g., ‘Kelman multiflex IOL’

2.Iris supported lenses, e.g., Singh-Worst’s iris claw lens

3.Posterior chamber lens

Name the absolute contraindications of an IOL implantation.

1.Proliferative diabetic retinopathy

2.Recurrent uveitis

When and who preformed the first successful

intraocular implant operation ?

Harold Ridley, a British ophthalmologist, performed the first IOL implantation on November 29, 1949.

Name a few perioperative complications of cataract operation.

1.Injury to cornea (Descemet’s detachment)

2.Accidental rupture of the lens capsule

3.Vitreous loss

4.Expulsive choroidal haemorrhage

Name some early postoperative complications of cataract extraction.

1.Hyphaema

2.Iris prolapse

3.Striate keratopathy

4.Flat (shallow) anterior chamber

5.Bacterial endophthalmitis

What are delayed complications of cataract extraction?

1.Cystoid macular oedema (CME)

2.Retinal detachment (RD)

3.Epithelial ingrowth

4.After-cataract

What are the types of after-cataract ?

1.Thin membranous after-cataract (thickened posterior capsule).

2.Dense membranous after-cataract

3.Soemmerring’s ring after-cataract

4.Elschnig’s pearls

Name the IOL-related complications.

1.Malpositions of the IOL, e.g., inferior subluxation (Sunset syndrome), superior subluxation (Sunrise syndrome), dislocation of IOL in the vitreous cavity (lost lens syndrome)

2.Toxic lens syndrome (IOL-induced iritis).

What are the advantages of an IOL implantation over spectacle correction of aphakia?

1.No magnification of the object.

2.No problem of anisometropia in uniocular aphakia.

3.Elimination of aberrations and prismatic effect of thick glasses.

4.Wider and better field of vision.

5.Cosmetically more acceptable.

What is postoperative management of cataract operation ?

1.The patient is asked to lie quietly upon his/her back for about three hours and advised to take nil orally.

2.For mild to moderate postoperative pain, injection diclofenac sodium (Voveran) may be given intramuscularly.

3.In the morning after about 24 hours of operation, bandage is removed and the eye is inspected thoroughly for any postoperative complication. Under normal circumstances, eye is redressed with one drop of 1 percent cyclopentolate, one drop of antibiotic and steroid drops and ointment. Daily dressing and bandaging continues for about 3 to 4 days and after that dressing is removed and tinted glasses are advised.

4.Antibiotic steroid eyedrops are continued for four times, three times, two times and then once a day for 2 weeks each.

5.After 4 to 6 weeks of operation, corneo-scleral sutures are removed.

6.Final spectacles are prescribed after about 8 weeks of operation

What do you understand by primary and

secondary IOL implantation ?

Primary IOL implantation refers to the use of IOL during surgery for cataract, while secondary IOL is implanted to correct aphakia in a previously operated eye.

How will you calculate the power of posterior

chamber IOL to be implanted ?

The power of the IOL to be implanted can be calculated using keratometry and A-scan ultrasound.

SRK formula commonly employed to calculate IOL power is as follows:

P = A – 2.5L – 0.9K; where P = IOL power in dioptres, A = specific constant of the IOL, L= axial length of the eyeball in mm and K= average keratometric reading.

IRIDECTOMY OPERATION

What is iridectomy and what are its types?

Iridectomy is an abscission of a part of the iris. It is of the following types:

Peripheral iridectomy

Key-hole iridectomy

Broad or sector iridectomy

What are the indications of iridectomy operation?

1.Abscission of the prolapsed iris

2.For optical purposes (optical iridectomy)

3.As a part of cataract operation

4.As a part of glaucoma operation

5.For removal of foreign body, cyst or tumour of the iris

6.In iris bombe formation (annular synechiae)

What is iridotomy and how is it performed?

Iridotomy means just incising a part of the iris. It can be performed by two methods:

Surgical iridotomy

Laser iridotomy

What are indications of iridotomy operation?

1.As a part of cataract surgery

2.Laser iridotomy for primary narrow-angle glaucoma

3.Four-dot iridotomy for iris bombe

SURGICAL PROCEDURES FOR GLAUCOMA

Name the various surgical procedures for glaucoma.

1.Peripheral iridectomy

2.Goniotomy

3.Trabeculotomy

4.Filtration operations

5.Seton operation (glaucoma valve operation)

6.Cycloablative procedures

Peripheral iridectomy operation is performed for

which type of glaucoma?

In primary angle-closure glaucoma during:

Prodromal stage

Stage of constant instability

Early cases of acute congestive glaucoma, i.e., when peripheral anterior synechiae are formed in less than 50 percent of angle

As a prophylaxis in other eye of the patient

What are filtration operations for glaucoma?

In filtration operations, passage is made for the drainage of aqueous humour into the subconjunctival space. Trabeculectomy is presently the most frequently performed filtration surgery. Other filtration operations which are now performed sparingly include: Elliot’s sclerocorneal trephining, punch sclerectomy, iridencleisis, Scheie’s thermal sclerostomy and cyclodialysis.

What are the indications of trabeculectomy operation?

1.Primary angle-closure glaucoma with peripheral anterior synechiae involving more than half of the angle.

2.Primary open-angle glaucoma.

3.Congenital and development glaucoma where trabeculotomy and goniotomy fail.

4.Selective cases of secondary open as well as narrow-angle glaucoma.

What are the advantages of trabeculectomy over other filtration operations ?

1.Incidence of postoperative shallow or flat anterior chamber is very less.

2.Incidence of postoperative hypotony is very low.

3.Chances of postoperative infection through the filtration bleb are low.

4.Quality of filtration bleb formed is good.

What is Seton operation ?

In this operation, a valvular synthetic tube is implanted which drains the aqueous humour from the anterior chamber into the subconjunctival space.

It is performed for neovascular glaucoma and intractable cases of primary and other secondary glaucomas where medical treatment and conventional filtration surgery fail.

What are cycloablative procedures ?

In these procedures, ciliary epithelium is destroyed to control the intraocular pressure. These procedures are used for absolute glaucoma. Commonly employed cycloablative procedures include: cyclocryopexy, cyclophotocoagulation and cyclodiathermy.