Ординатура / Офтальмология / Английские материалы / Pediatric Opthalmology_Mukherjee_2005

1.Ciliary block57. The normal flow of aqueous is from posterior chamber to anterior chamber via pupil and from anterior chamber to canal of Schlemm through trabecular meshwork. Hardly any aqueous percolates to the vitreous. In case of pupillary block, flow of aqueous from posterior chamber to anterior chamber is impeded but aqueous does not find its way into the vitreous. In case of malignant glaucoma there is severe spasm of ciliary body, the ciliary body moves centrally towards the lens. In this process the ciliary body may come in actual contact with peripheral part of lens when it is present. In case of intracapsular lens extraction the ciliary body may throttle the vitreous cone projecting in the pupillary area. In phakic eyes the iris lens diaphragm moves forwards shallowing the AC and obliterating the angle. Here the second mechanism takes over i.e. misdirection of aqueous flow.

2.Aqueous misdirection55. The aqueous instead of finding its usual anterior path via pupil, drains into the vitreous or behind the vitreous. Retrovitreal accumulation is assisted by posterior vitreous detachment. The ever increasing aqueous pushes the vitreous body forward, which in turn pushes the iris lens diaphragm forward. This along with ciliolenticular block worsens the flow of aqueous via conventional anterior route causing rise of tension.

Diagnosis. The condition is diagnosed by severe post operative pain and unexplained diminished vision. On examination the cornea is edematous, the anterior chamber is very shallow, the pupil is constricted and tension is very high. Gonioscopy when possible shows almost obliterated angle. Ocular ultrasonography reveals ciliolenticular block and aqueous in or behind the vitreous.

Treatment. Treatment consists of59, 60

1.Lowering of tension by

A.reducing formation of aqueous by carbonic anhydrase inhibitors orally and local instillation of beta blockers or alpha agonists.

B.Reducing volume of vitreous by IV 20% mannitol, oral glycerine.

2.Relieving pupillary block :

A.Use of strong cycloplegic i.e. atropine sulphate 1% drops two times a day. If necessary 5% to 10% phenylepherine or 1% tropicamide every five minutes for five times may be supplemented with atropine Pilocarpine is contra indicated. It worsens the ciliary and pupillary block.

B.If medical treatment fails, surgical intervention is required that may be surgical iridectomy, laser iridotomy, rupture of anterior vitreous faces by laser or mechanically in aphakic eyes. In phakic eyes a subtotal vitrectomy may be required. Sometimes aspiration of aqueous entrapped in vitreous may also give relief.

Closed globe surgical procedures that cause glaucoma60 :

Glaucoma following scleral buckling. Glaucoma following scleral buckling has two phases. The first is intra operative, where indentation of the sclera and tightening of the scleral buckle causes sudden rise of intraocular tension. The raised tension may cause central retinal artery obstruction and if not relieved may cause permanent damage. It is mandatory that all retinal surgeries be done with indirect ophthalmoscope and while tying the buckle, the pulsation in the central artery of retina be monitored. Absence of pulsation requires immediate lowering of tension either by loosening the sutures or intra venous injection of a bollus of acetazolamide or mannitol.

The second phase is late and chronic rise of tension that develops after six to seven days and may go unnoticed. The tension is rarely very high. These eyes generally have low scleral rigidity so recording of tension by indentation tonometer gives a false low tension.

Paradoxically some of the eyes that have undergone scleral buckling may develop hypotony that may last for years.

Glaucoma following Nd-YAG posterior capsulotomy, laser trabeculoplasty and iridotomy :

All these conditions have two types of pressure elevation. The first - that is seen within one hour following the procedure. This is seen in twenty five percent of all eyes, is transient and controlled by local beta blockers two times a day for two to three days. Possibility of this type of rise of tension should always be remembered in paediatrics patients who have cent percent chance of developing PCO following extra capsular cataract extraction with or without IOL. The acute rise of tension is most probably due to lens particles blocking the trabecular meshwork. The second type of glaucoma is late onset of glaucoma in some patients only. The cause is not well understood.

Uveitis as Cause of Glaucoma in Children

Glaucoma secondary to anterior uveitis is one of the major causes of childhood blindness.60 It’s presentation is so varied that a high degree of suspicion is required to diagnose the condition specially in children where an immature eye is liable to suffer visual loss if glaucoma is not treated well. The condition is over shadowed by the overwhelming signs of anterior uveitis.

The pitfall can be eliminated if tension is monitored on every visit. Intraocular tension under local anaesthesia can be recorded in children above five years with little persuasion and reassurance. Similarly recording of vision with P.H. retinoscopy and fundus examination should also be done more frequently. It is better to do gonioscopy examination every three months. Pressure changes in uveitis swing between hypotony to moderate elevation. Generally tension in anterior uveitis is either normal or low to begin with, both the conditions can culminate in glaucoma over a period of time61.

Initial low tension in anterior uveitis is caused due to ciliary shut down, which results in hypo secretion of aqueous in presence of normal resistance to outflow. However persistent low tension is an important cause of formation of peripheral anterior synechea that causes increased resistance to aqueous outflow. This leads to gradual rise of IOP which reaches normal range or may overshoot to cause glaucoma.

Rise of intraocular tension can be acute, intermediate or delayed63,64. Basically there are two types of secondary post inflammatory glaucoma :

(a) Open angle glaucoma and

(b) closed angle glaucoma65. The latter can either be with pupillary block or without pupillary block. Incidence of open angle secondary glaucoma is more common than closed angle. Exact mechanism of raised intraocular tension is not well understood. It is multifactorial that may work separately or in combination.

Probable causes of open angle glaucoma in uveitis66

(i) Spread of inflammation into trabeculum leading to trabeculitis. Edema of trabeculum results in narrowing of trabecular meshwork that impairs outflow of aqueous.

(ii) This is worsened by increased viscosity of plasmoid aqueous which finds it difficult to pass through narrow meshwork.

(iii) The cellular debris and iris pigments may plug the pores of the meshwork. (iv) Prolonged use of steroid in a steroid responder causes rise of tension.

(v) Release of prostaglandin also plays an important role in causing glaucoma.

(vi) On long run sclerosis and scarring of trabecular meshwork may be the cause of rise in intraocular tension.

Probable cause of angle closure glaucoma in uveitis :

(i) Closed angle glaucoma with pupillary block - Extensive posterior synechiae leads to formation of ring synechiae which prevents aqueous to escape through the pupil into the anterior chamber. This pushes the iris forward in the form of iris bomb’e narrowing the peripheral part of anterior chamber and formation of peripheral anterior synechiae. However 360° of posterior synechiae without iris bombe can also cause rise of tension. This is worsened if the pupil is small and covered by exudate. Thickened iris, miosis and plasmoid aqueous also raise tension, so does release of prostaglandin.

(ii) Closed angle glaucoma without pupillary block. This is mostly due to deposition of inflammatory debris on the trabecular meshwork, subsequent contracture of iris over the trabecular meshwork. A paradoxical situation arises when dilation of pupil causes embarrassment of the angle. This happens if the angle is already narrow. Multiple peripheral anterior synechiae may form a pseudo angle proximal to trabeculum preventing aqueous to reach true angle. Swollen ciliary body may push the lens iris diaphragm forward, narrowing the angle, resulting rise of IOP.

Diagnosis of glaucoma in anterior uveitis is often missed unless it’s possibility in every case is kept in mind. It is a misconception that glaucoma is rare in children in uveitis. It is a major cause of childhood blindness62. In all cases where vision is low and does not improve with PH, tonometry, retinoscope and ophthalmoscopy should be performed. Gonioscopy helps to differentiate between an open and closed angle.

Management. In acute stage and to some extent chronic rise of tension can be lowered by usual treatment of anterior uveitis with cycloplegic and steroids otherwise management depends whether it is an open angle or close angled glaucoma.

Open angle glaucoma in uveitis is managed by :

Continuing treatment with cycloplegic and steroid/non steroidal antiinflammatory

drugs.

Treatment of open angle glaucoma by instillation of local, beta-blockers, alpha agonist or carbonic anhydrase inhibitors. The last is least effective in children, miotics and prostaglandin analogs are contra indicated.

Systemic use of carbonic anhydrase inhibitors should be employed for short period. Slow release, CAI are better tolerated by children.

Surgical treatment consists of modified goniotomy64, trabeculodialysis and trabeculectomy. In rare cases aqueous drainage devices may be required.

Closed angle glaucoma with pupillary block is managed by establishing a passage between the anterior and posterior chamber first therapeutically and if it fails either by laser or by surgery.

Therapeutic measures used are strong cycloplegic to break the synechiae. Frequent use of steroid helps in lysis of synechiae. Addition of epinephrine has synergistic action with cycloplegic that enhances mydriasis. Betablockers and alpha agonists do not have any action on size of pupil, they are used to lower the intraocular tension. Miotics and latanoprost are contra indicate. Acute rise is controlled by oral carbonic anhydrase inhibitors.

The argon laser or NdYAG laser iridotomy establishes a permanent passage between anterior and posterior chamber. Surgical iridectomy is indicated when facility of laser iridotomy is not available or when such procedure has failed.

Closed angle glaucoma without papillary block is treated medically by betablockers and alpha agonist, surgical management consists of trabeculactomy.

Steroid Induced Glaucoma in Children

Steroid induced glaucoma is an avoidable iatrogenic glaucoma. It is seen in steroid responders and those who have family history of chronic open angle glaucoma. It can occur in any age and sex. However it is more frequent in children67. Steroid induced glaucoma is secondary open angle glaucoma. Its physical findings are similar to COAG. Pressure elevation depends on many factors that include - response to steroids, family history of chronic open angle glaucoma, strength of drops used, frequency and duration of steroids used. It is more common in steroids like prednisone, prednisolone, dexamethsone, beta methasone, and triamsonolone. It is less common in steroids like medrysone and flurometholone67. However none of the steroids are free from intraocular tension raising property. Generally glaucoma becomes evident after three weeks of instillation of dexa or beta methasone in high steroids responders. It may take months in low responders with same regime.

All routes of administration of steroids are fraught with glaucoma. Commonest being ocular use as drops or ointment. This is followed by periocular use. Systemic use of steroids are more likely to result in glaucoma than skin ointment, inhalers and nasal spray.

On the top of the list of common ocular conditions that culminate in steroid induced glaucoma in children is spring catarrh where unnecessary, prolonged use of steroids that use cortisol as foundation are the most offending drugs. This is followed by anterior uveitis, trauma both accidental or surgical. The surgical condition that need to be monitored for rise of IOP are : aphakia, pseudoaphakia, glaucoma surgery and keratoplasty.

The exact mechanism of rise of tension following use of steroid is not known. It is said to be enzyme related.65

Clinical presentation of steroid induced glaucoma in children is similar to that of chronic open angle glaucoma. Only difference is that in most of the eyes with steroid induced glaucoma

tension falls within normal limits in two to three weeks after stoppage of drug. Associated field and fundus changes are permanent, these changes may be confused as due to low tension glaucoma in later life.

The eye is non congested except in spring catarrh where the eyes remain red due to existing allergic conjunctivitis. The anterior chamber is of normal depth and the angle is wide open. In rare instances where steroid induced glaucoma develops before three years of age, the eye may be buphthalmic.

All children under steroid therapy local or systemic, should be warned about possibility of glaucoma, these children should get their IOP and vision recorded every three months and disc evaluated twice a year.

Treatment consists of :

1.Prophylaxis

2.Medical treatment

3.Surgical treatment

1.Prophylaxis :

(a) Awareness among treating ophthalmologic, paramedical personnel, pediatrician, general physician and dermatologist about possibility of steroid induced glaucoma in children.

(b) Parents should be warned about possibility of steroid induced glaucoma especially in spring catarrh. It should be emphasised upon them that, “no child goes blind due to spring catarrh but hundreds of children loose sight due to steroid”.

(c) use of lowest dose of steroid for shortest period that gives the child comfort.

(d) Residual allergy, inflammation should be treated by non steroidal antiinflammatory drugs, local antihistamine and astringents.

2. Medical treatment :

(a) Once it has been established that the child has steroid induced glaucoma, the drug should be tapered and steroid replaced by non steroidal antiinflammatory drugs. This generally brings down the tension to normal range.

(b) If tension remains high in spite of discontinuation of steroid or steroid can not be discontinued, the tension is brought down by miotics, beta blockers, alpha agonist, epinephrine and its pro-drug. In case the child was suffering from uveitis, miotics and latano prost are contra indicated.

3. Surgical treatment :

Only a few children may require surgical intervention. Eyes with steroid induced glaucoma do not respond well to laser trabeculoplasty. Surgery of choice is trabeculectomy.

Glaucoma following blunt injury can be caused by :

(i) Blood and blood constituents in anterior chamber.

(ii) Recession of angle of anterior chamber. (iii) Phacogenic

Glaucoma due to blood and blood constituents in the anterior chamber constitute a group of conditions that are grouped under hemogenic glaucoma69 that may present as :

—Glaucoma secondary to total hyphaema

—Hemolytic glaucoma

—Ghost cell glaucoma

Out of these, glaucoma secondary to total hyphaema red cell glaucoma67 is most common following severe blunt injury. The eyeball is compressed anterio posteriorly pushing the aqueous laterally. The force of compressed aqueous acts as a shearing force at the angle and causes damage to the root of the iris, and ciliary body. Normal iris generally does not bleed between the root and the pupil but may bleed when injured at the root. The ciliary body bleeds more frequently than iris. The bleeding may occur within few minutes of injury or may be delayed for three to four days. Bleeding after four days is more severe than initial bleeding. Rebleeding is frequent.

There is an acute rise of tension as blood fills the whole of the anterior chamber blocking the trabecular meshwork all around. The blood especially the clotted blood may cause pupillary block, worsening the condition. The rise of tension varies between moderate to very high.

With sudden rise of tension there is severe ocular and periorbital pain. Pain radiates on the same side of the head. The eye is generally congested with lacrimation, vision is reduced to perception of light or at the most counting finger from close quarter, vision improves as blood settles down at the lower parts of the anterior chamber. The other cause of diminished vision and lacrimation is associated corneal haze. The child is generally irritable may have bouts of vomiting.

The fresh blood in anterior chamber is visible through the transparent cornea. The parents may be able to say that there is blood in the eye. With passage of time, the blood starts clotting and its colour becomes darker, ultimately it assumes black and oval shape, such a condition is called eight ball or black ball hyphaema. There may be re-bleeding, that may be spontaneous or follow repeat trauma. There may be rebound bleeding following instillation of epinephrine or its derivatives.

Total hyphaema of more than five days duration and raised intraocular tension is most likely to develop blood staining of cornea.

Blood staining of cornea is due to infiltration of endothelium and posterior stroma by blood constituents. As the epithelium is also effected there is associated haze of cornea with epithelial edema.

Glaucoma secondary to total hyphaema requires early treatment to :

1.Prevent blood staining of cornea, which may last for years causing prolonged diminished vision that leads to squint and amblyopia.

2.Protect the optic nerve from glaucomatous neuropathy and permanent visual loss.

Management of glaucoma secondary to total hyphaema :

The management consists of :

1.Immediate steps to prevent glaucoma.

2.Management of glaucoma.

Immediate management is essentially treatment of total hyphaema, which consists of :

1.The child is hospitalised to minimise movement.

2.The affected eye is bandaged over a pad. Bilateral patching does not have advantage over unilateral bandage.

3.The head end is kept raised. This helps the heavy blood particles to settle down at the bottom of the AC to facilitate opening of trabecular meshwork in the upper part.

4.Instillation of local drugs71 - Miotics are contra indicated as they may worsen associated anterior uveitis. Epinephrine is known to cause rebound bleeding hence it is also not used. cycloplegics give relief to cyclopasm and reduce pain. Role of local steroid has not been proved beneficial in every case. Beta blockers are helpful to keep IOP low hence they may be used not only in proved glaucoma but also as prophylaxis against rise of tension.

If the child bleeds repeatedly without trauma, the child should be investigated to exclude sickle cell disease or other bleeding disorders.

The child may be put on oral fibrinolytic i.e. a aminocaproic acid in a dose of 50 mg/kg/ day in consultation with paediatrician.

Raised intraocular tension is brought down by :

1.Oral carbonic anhydrase inhibitor in dose of 10mg-20mg/kg/day in divided dose with potassium supplement.

2.Oral glycerine in dose of 1 to 1.5 cc/kg/day in two divided doses.

3.Intravenous mannitol in dose of 1 gm to 1.5 gm/kg may be given in fast drip. This is generally done in cases where paracentesis is planned.

If tension does not come down within forty-eight hours with medical treatment, blood is evacuated either by simple paracentesis or washed with balanced salt solution. To clear clotted blood two stab incisions are given, one at temporal side of the cornea and the other opposite to it. Through the first viscoelastic is introduced which forces the clot out through the other hole.75 Visco-elastic itself is then washed with BSS and anterior chamber reformed, the eye is observed for rebleeding and rise of tension. Once the acute episode has passed, the eye is kept under watch for delayed rise of tension over years which is generally due to recession of angle of anterior chamber. (see page 265).

(b) Hemolytic glaucoma69,73. This secondary wide-angle glaucoma is less common than glaucoma associated with hyphaema. It may be an early or late feature in blunt injury. In hemolytic glaucoma the break down products of blood in anterior chamber i.e. red blood cells or hemosiderine are phagocytosed by large macrophages that plug the trabecular meshwork and cause rise of intraocular pressure in milder form, the condition is self limiting. However it is better to keep the tension within normal range in all cases of hyphaema by

betablockers and alpha agonist. Miotics epinephrine and latanoprost are contra indicated. Some clinicians feel that hemolytic glaucoma is a milder form of ghost cell glaucoma.

Ghost cell glaucoma69, 70, 73. The secondary open angle glaucoma was previously known as erytholastic glaucoma.75 It is mostly seen in vitreous haemorrhage with broken anterior vitreous face. It is also met within total hyphaema especially in eight ball hyphaema. In adults it is mostly seen following lens extraction and pre-existing vitreous haemorrhages. If the vitreous face gives away, the blood finds its way to anterior chamber to cause ghost cell glaucoma.

In children traumatic vitreous haemorrhage with subluxated or dislocated lens can cause ghost cell glaucoma.

The mechanism of glaucoma is multifactorial. The RBCs which are circular, biconvex, and pliable can pass through trabecular meshwork without any obstruction. When these are converted into larger, spherical, rigid bodies in the vitreous, these cells contain denatured haemoglobin called Heinzbodies76 and are called ghost cells.

The ghost cells due to rigid walls and spherical shape, fail to pass through the pores of the trabeculum causing rise of intraocular tension. These cells may collect at the bottom of the anterior chamber with a soft-white or khaki coloured pseudo hypopyon. It takes red cells ten to fifteen days to be converted into ghost cells in the vitreous.

Rise of intraocular tension that is mild to moderately is directly proportionate to number of ghost cells present, with too many ghost cells, the IOP may be raised sufficiently to cause pain, photophobia and diminished vision due to corneal edema.

Management consist of lowering of intraocular pressure by standard anti-glaucoma drugs and keep it within normal range with minimum drug. If medical treatment fails, standard surgical procedure may be required. Miotics epinephrine and latanprost are contra indicated.73

Glaucoma secondary to angle recession71, 77, 80. Angle recession glaucoma may develop months or years after blunt injury. Many a times the patient may even forget about receiving blunt injury in childhood or may think such trivial incident not worth mentioning. This makes enquiry about blunt trauma mandatory in all cases of uniocular wide angle glaucoma.

Angle recession glaucoma is generally uniocular. Being traumatic it is more common in boys. In the beginning, it may be masked by hyphaema and hemogenic of glaucoma. Initial hypotony, which is very common, does not exclude possibility of angle recession glaucoma in future. About ninety percent of eyes with blunt injury have some degree of angle recession, only ten percent of eyes with angle recession develop glaucoma. Recession may involve only a small sector or may be extensive. Recession less than 180° is less liable to develop glaucoma. Recession more than 270° is most likely to develop glaucoma.

The recession of angle which is in fact a laceration on the face of ciliary body that extends between the longitudinal and circular muscle develops immediately following blunt injury. The recession may initially be missed due to corneal changes and associated hyphaema or when not suspected. Hence all eyes with blunt injury should undergo gonioscopic examination after six weeks. Bilateral gonioscopy facilitates comparison between normal and injured eye.

The parents of injured children should be told about possibility of glaucoma in later life and instructed to get the child’s eye examined for vision, rise of tension, changes in angle and disc every six months and then yearly.

It has been widely noticed that angle recession glaucoma is more common in persons who have positive history of wide angle glaucoma in the family. The child may develop chronic simple glaucoma in the uninjured eye later.

The exact mechanism of development of glaucoma in angle recession is not well understood. One point is established that angle recession perse does not cause glaucoma. It is the effect of trauma on the trabeculum that is the prime suspect in producing glaucoma. A membrane like structure covers the trabecular meshwork facing the pupil, which is actually proliferation of Descemets membrane.

The force may extend in the trabecular meshwork and disrupt it that heals by scarring. The force may rip off the ciliary body from the scleral spur and cause cyclodialysis. Iridodialysis is also very common.

Diagnosis is confirmed by gonioscopy. Bilateral gonioscopy by Koeppe lens helps to compare the findings of injured eye with the normal eye, slightest deepening of AC on the injured side is always suspicious finding.

Frank tremulouness of iris with deep chamber denotes subluxation of lens. Common findings include mild to moderate mydriasis, widening of ciliary band. The width of ciliary band is irregular, whitening of scleral spur and the trabecular meshwork. The trabeculum may be sprinkled with iris pigment giving a false impression of pigmentary glaucoma. The angle is wide.

Treatment of angle recession glaucoma is similar to any secondary open angle glaucoma, which consists of local instillation of betablockers or alpha agonist. Pilocarpine is not favoured because it is presumed that in a traumatised eye with damage to the trabecular meshwork, the outflow is diverted to uveo-scleral outflow that is impaired by miotic79 hence latanoprost may be more effective than miotic. Sustained released carbonic-anhydrase inhibitors may be given orally for short term, local carbonic anhydrase do not have much effect in children.

When glaucoma can not be brought under control, surgery may have to be employed. Argon laser trabeculoplasty does not give uniform result78. Conventional trabeculectomy with mitomycine-C or 5 fluro uracit gives better results77.

Traumatic phacogenic glaucoma

Following blunt injury, the lens may be dislocated or subluxated. Blunt injury rarely cause fast opaification of lens which is very common in penetrating injury. Hence blunt trauma rarely causes phacogenic glaucoma except when either the dislocated lens has come in AC or is trapped in pupil. Rarely the lens may become intumescent and cause both pupillary and angle closure glaucoma.

Glaucoma in post surgical status (page 355)

Non traumatic Phacogenic glaucoma in children81, 82. Lens may cause glaucoma by any of the following causes separately or in various combinations. The causes can be congenital manifesting in childhood or acquired. Opaque lens is more likely to cause glaucoma than transparent.

(a) Phaco-morphic (i) Sherophakia (ii) Microphakia (iii) Tumescent

(b) Phacotopic

(i) Congenital ectopic

(ii) Acquired —Subluxated —Dislocated

—Incarcerated in the pupil.

(c) Phacolytic

(i) Cortical matter

(ii) Due to leak of protein (iii) Phacoanaphylactic

Phaco morphic glaucoma. This type of glaucoma is caused by a small relatively spherical lens that closes the pupil like a ball and socket. The pupil may either be normal or miotic. Small pupil is more likely to cause pupillary block glaucoma. This type of glaucoma is relieved by mydriasis and is called glaucoma inversus or paradoxical glaucoma.

Intumescent lens. Intumescent lens as cause of glaucoma is mostly seen in age related cataract where a lens swells to cause pupillary block and secondary angle closure. The same effect is brought about in children when aqueous finds its way through a microscopic wound mostly in blunt trauma and causes the lens to swell. The swollen lens causes pupillary block and secondary angle closure.

Management consists of lowering of tension by oral acetazolamide, local beta blockers. Local steroids may be helpful to supress associated uveitis. Once tension has been brought to safe limit an ECCE with PCIOL is the best available treatment.

Cortical matter glaucoma. This is a step ahead of intumescent of lens. Here the capsule is ruptured either accidentally as following penetrating injury or has been surgically cut to perform ECCE. The condition is very common following needling in children either for congenital or traumatic cataract. The anterior chamber is filled with soft cortical matter that blocks both pupil and the angle. Management consists of removal of as mush of cortical matter as possible.

Microscopic leak of denatured lens protein, which does not cause antigen antibody reaction is ingested by macrophages that swell up and block the trabecular meshwork leading to secondary open angle glaucoma.

Management consists of lowering IOP by any standard method followed by removal of

lens.

Phacoanaphylatic glaucoma—In contrast to above, in rare instances, the lens protein acts as an antigen and causes severe local reaction in the form of anterior uveitis and is associated with glaucoma. This is rare in children.