enhancement and help in light adaptation.
Five-year-old Asma Sultana has a pathetic tale to tell. Like her two elder sisters Rehana Sultana (6) and Najma Sultana (7), she can't tolerate light. Bright light makes her virtually blind. The three girls were diagnosed by doctors at LV Prasad Eye Institute in Hyderabad as suffering from a strange eye problem called cone dystrophy.
Their father, a daily labourer, deserted the girls after he noticed that the eye defect could not be rectified. The girls' mother took care of them and admitted in a local government school. But soon the problems began for the girls as they could not see the black board or move freely in the open.
The mother then took the girls to LV Prasad Eye Institute where doctors prescribed some simple techniques to reduce the problem. The girls now have an improved vision and play with other children. The doctors helped the girls overcome the defect by advising sunglasses. The girls were given absorptive or tinted lenses that reduce glare.
They were also advised to wear hat for shade from sunlight."There is no permanent treatment or cure to photophobia but better eye management and eye care techniques will reduce the trouble. Lubricant eye drops will also help. Patients find it difficult to drive during night because of headlights glare. Even during the day time they feel uncomfortable in the sunlight," says senior ophthalmologist Dr Sreekumar Reddy.
The problem with these three girls was that they are extremely sensitive to light and lower their gaze while walking. They squint and blink at the slightest glare. Cone dystrophy in their eyes has led to this rare condition called photophobia or hyper sensitivity to light.
Andhra Pradesh has thousands of children and adults with photophobia and the number is increasing with the each passing year. Neglect of ophthalmic care by parents in case of young children is said to be one of the causes for low vision coupled with sensitivity of light. As many as five crore people suffer from the low vision problem in the country and quite a considerable number of them complains of photophobia.
Though there are no official statistics on the number of photophobia patients in the country, the problem is quite common in albinos or "moon-children" and those with low vision. People who suffer from various eye diseases like ocular albinism, cataract, retinitis pigmentosa and diabetic retinopathy also complain of sensitivity to light like these girls. "For a clear image to appear on the retina a clear medium is needed. In case of opacity in the eye the intraocular light gets scattered bringing down the vision levels. Such eyes become extremely sensitive to light and glare. People with photophobia see glare in light that appears normal for healthy people," says ophthalmologist Dr Altaf Akbar.
Eyecare specialists suggest that coloured lenses with specific tints to restrict different wavelengths of light will do wonders. The patient may choose from a wide range of colours that suit his or her eyes.
Filters, that come in different tints at various levels of absorption and different cut-off points, provide contrast
enhancement and help in light adaptation. Corning photochromic filters are also useful since short wavelength light has been shown to cause hazy vision, reduced contrast and discomfort. The photochromic filters filtering out blue light in the visible portion of the spectrum, at the wavelengths that create problems for the photophobic patients.
They are specially designed to filter short wavelength light.Some ophthalmologists are of the view that ultra violet shields (of blue spectrum) provide protection for 100 per cent UV and visible light. The filter in the shields eliminates near infrared 100 per cent UV and provides visible light protection.
For those who find it a problem while reading because of reflection from white pages may go in for typoscope (a black, non-reflective plastic card with a rectangle cut out of it).
A hat with a wide brim or a sun visor can help cut down glare and facilitate mobility outdoors.
When photophobic patients move between places of different lighting levels (say from sunlight to a closed room or vice versa), doctors suggest that they pause a while, take off or put on the sunglasses depending whether they are moving in or out of sunlight. This allows their eyes to adjust without causing any visual discomfort.