Loss of vision in a white eye

This is one of the common presentations of eye disease. Loss of vision in a white eye can be slow or fast. If a patient loses his vision slowly over months or years, he may have: (1) A corneal scar. (2) Cataracts. (3) Glaucoma. (4) A refractive error. Or, (5) disease of his retina due to: (a) Senile macular degeneration. (b) Retinitis pigmentosa. (c) Chloroquine maculopathy. (d) Old macular scars. Or, (6) optic atrophy. If he loses his vision suddenly over minutes or days, the cause is usually inflammatory or vascular (see below). If he complains that he cannot read, he usually has has presbyopia (24.8).

Corneal scars cause 70% of blindness in children and 25% in adults in the developing world. A corneal scar can be: (1) Diffuse. (2) A circumscribed white patch (leucoma). (3) A staphyloma, which is a bulging of the cornea forwards between the lids, due to the thinning, caused by previous ulceration. (4) Pthisis bulbi, which is disorganization of his entire eye, leaving it small and shrunken. Bilateral scarring follows ophthalmia neonatorum, vitamin A deficiency, traditional eye medicine, and trachoma. Unilateral scars are more likely to be caused by corneal ulceration due to bacteria, the herpes simplex virus, fungi, or trauma.

Cataracts cause about one half the blindness in the developing world, where they blind about one person in 200. 85% of cataracts are ''senile', and the rest are either congenital or familial, or due to trauma, iritis, or diabetes. A patient with a cataract presents with gradual loss of vision, in one or both his eyes. His corneae are clear, and there is an opacity in his pupil(s). A cataract can be immature (making his pupil grey), or mature, or hypermature (making it white). Sometimes a cataract swells, pushes the iris forwards, occludes the angle of his eye, and causes secondary glaucoma.

Removing cataracts is a standardized and repetitive task; it is also a skilled one and is never urgent, so it is not described here. If you want to remove them, apprentice yourself to an expert for several months, and try to remove at least 50 under supervision. Or, send an assistant to learn this skill. Cataracts can also be removed on a mass scale, particularly in Asia, in special ''eye camps'.

In good hands the chance of success is over 90%. If a patient is operated on for the right indications, even moderate success in one eye only will enable him to be independent again. He is usually happy if he can see well enough to find his way about his home area. You will have to weigh up the benefits, and the risks, because vision without a lens is not normal vision.

There are two methods: (1) Removing the whole of his lens, within the capsule of the cataract (intracapsular extraction), which is the preferred method in the developing world. (2) Opening the anterior capsule, removing the cortex and lens, and leaving the posterior capsule (extracapsular extraction). This is safer in younger people ([lt]30 years).

LOSS OF VISION [s8]IN A WHITE EYE One or both eyes? Gradual or sudden? Family history? Any external factors such as trauma?

COMMON CAUSES [s7]OF GRADUAL LOSS OF VISION This is the patient who cannot see normally, and whose eyes are not reddened by conjunctivitis or ciliary injection. Examine him as in Section 24.1.

CORNEAL SCARS If the cause of the scar is still present, and it is getting worse, arrest it. Causes include scratching of the cornea by the inturned eyelashes of trachoma (trichiasis, 24.13; vitamin A deficiency causes an acute ulcer in young children, and does not cause progressive scarring). When you are sure that you have done all you can to prevent his scar progressing, manage him like this:

If he still has adequate vision in his other eye, he will not be severely disabled, and no treatment is indicated.

If he cannot see light at all, explain that nothing can be done.

If he is blind, and has a central leucoma which obscures his pupil, with an area of clear peripheral cornea, refer him for a optical iridectomy. This will give him an artificial pupil peripherally, behind his area of clear cornea, and should give him enough vision to make him mobile. It is contraindicated if he already has enough vision for mobility, or if he has no clear peripheral cornea.

If he is blind due to diffuse corneal scarring which has not made his eye perforate, consider referring him for corneal grafting. This is difficult and is usually impractical, because grafts and experts are scarce. Preferably, his cornea should have few vessels in it or none.

If his eye is blind and painful, consider eviscerating or enucleating it (24.14).

If he has any other kind of corneal scar, for example a unilateral corneal scar or pthisis bulbi, there is no point in referring him.

CATARACTS (1) Measure his visual acuity accurately in both eyes. His pupils should react briskly to light. If they don't, suspect that he also has some other condition, such as optic nerve disease. (2) Measure his IOP to make sure that his loss of vision is not due to glaucoma (24.6). (3) Dilate his pupil and examine his red reflex with an ophthalmoscope to assess how dense his cataract is, especially if it is immature. If you can easily see his optic discs, his cataract is not yet dense enough to be worth extracting.

INDICATIONS FOR EXTRACTION. (1) To improve his sight. (2) To treat complications, especially secondary glaucoma.

If he has bilateral cataracts, operate when his acuity in both eyes has fallen to [lt]6/60 (CF at 6 m).

If he has a unilateral cataract, surgery is only indicated to treat or prevent secondary glaucoma, or uveitis. It will not improve his sight.

If he has already lost the sight in his other eye for any reason, and he now has a cataract in his remaining eye (cataract in an only eye), delay surgery until he has difficulty getting around by himself and is nearly blind ([lt]CF 3 m), because any complication will make him totally blind.

If he has already had one cataract removed and is happy with his aphakic spectacles, his second cataract can be operated on at any time. But, because he can now see, he will be a low priority.

If his cataract is not ready for extraction, or if extraction is impossible, atropine ointment weekly, or minus (concave) glasses may improve his sight.

CONTRAINDICATIONS. (1) Unilateral cataracts with adequate sight in the other eye. (2) Bilateral small immature cataracts with acuity [mt]6/60 in both eyes together[md]review his progress in 3[nd]6 months.

If a cataract extraction is indicated, refer him.

POSTOPERATIVELY, if you have to care for him after he has been operated on by someone else, watch for a leaking wound (with or without iris prolapse), infection, bleeding, and a raised IOP. Gently open his lids, and examine his eye with a torch. If there is any iris prolapse, he must go back to the theatre, and have the iris excised and the wound resutured.

If his cornea is hazy with a striate pattern (striate keratitis), it will probably settle.

If his anterior chamber is shallow, the wound may be leaking. A firm double pad and bandage applied to his eye for 24[nd]48 hours may stop the leak.

If there is blood in his anterior chamber (hyphaema), pad his eye and keep him in bed.

If there is pus in his anterior chamber (hypopyon), it may indicate postoperative infection (endophthalmitis). His eye is likely to be painful and his visual acuity very low. Give him subconjunctival gentamicin (24.1), topical antibiotics hourly and chloramphenicol by mouth.

If his red reflex is absent, there is some opacity in his media.

If he complains of much pain and his cornea is hazy, his IOP is probably raised (aphakic glaucoma); measure it. (1) His vitreous jelly may be blocking his pupil. Immediately dilate his pupil with cyclopentolate and phenylephrine drops, followed by atropine ointment for several weeks.

If his wound is tight, his cornea clear, his anterior chamber deep and clear, and his pupil black, all is well. Give him [+]10 aphakic spectacles and discharge him between the 3rd and 10th postoperative day.

RARER CAUSES [s7]OF GRADUAL LOSS OF VISION IN A WHITE EYE Examine his macula and his optic cup with particular care.

If an old person has gradual loss of central vision, atrophy, and irregular pigment at his maculae, suspect senile macular degeneration. There is no treatment.

If he has pale, white, flat optic discs (distinguish these from the pale cupped discs of glaucoma), and normal maculae, he has optic atrophy. Try to find the cause (there are many, including a space-occupying lesion around the optic chiasma). There is no treatment.

If he has gradual loss of vision at any age, often starting with night blindness, a family history, and dark pigmentation which follows his retinal vessels and takes the form of ''bone spicules', suspect retinitis pigmentosa. There is no treatment.

If he has gradual loss of central vision and has taken excessive doses of chloroquine ([mt]10 tablets weekly for [mt]1 year), suspect chloroquin maculopathy. His macula has a typical ''bull's eye' pattern with a dark centre and a paler surrounding ring. Stop chloroquin. There is no treatment.

If he has old macular scars (large white areas with black edges, often around his optic disc and his macula), they may be due to previous toxoplasmosis or toxocariasis. There is no treatment.

SUDDEN LOSS OF VISION [s7]IN A WHITE EYE(S) He has lost his vision over minutes or days, in one or both eyes, which are white.

If at any age he has steadily lost his vision over 24 hours, in one eye or occasionally both his eyes, suspect posterior choroiditis due to toxoplasmosis or other causes. The important sign is inability to see his retinal vessels due to hazy media caused by inflammatory cells in his vitreous. He may respond to systemic steroids, and he may resolve spontaneously. Give him atropine until the inflammation has resolved.

If symptoms started with a flash of light followed by black objects floating in his field of vision, and then a curtain or cobweb across it, suspect retinal detachment. Part of his retina may look grey-green. Dilate his pupil and examine his fundus. You will see an abnormal red reflex in one part of his fundus, with elevation of part of his retina, and tortuosity of its vessels, which are difficult to focus on. Expert surgery may save his sight.

If he has instantaneous loss of vison, suspect occlusion of his central retinal vein (a swollen disc with many haemorrhages all over his retina), or artery (a swollen disc, oedema of his retina, and often a cherry-red spot at his macula). There is no immediate treatment. If he has central retinal vein thrombosis, follow him for at least 3 months, because he may develop secondary glaucoma, which needs treatment.

If he has loss of central vision with an abnormal pupil response to light, suspect optic neuritis (any age, usually in the 3rd and 4th decades, and usually unilateral). His media and optic disc are usually normal. He will usually improve over about 8 weeks. Bilateral optic neuritis following methyl alcohol or drugs (quinine) is permanent. There is no specific treatment.