Indirect evaluation of corneal apoptosis in contact lens wearers by estimation of nitric oxide and antioxidant enzymes in tears.

BACKGROUND: Contact lens induced trauma to the corneal epithelium results in increased release of inflammatory mediators. The keratocyte apoptosis is directly related to epithelial injury and has been correlated with increased production of nitric oxide. Potent antioxidant enzymes protect cells from oxidative damage by inactivating reactive oxygen species and thus inhibiting apoptosis. This study aims at determination of total nitric oxide and antioxidant enzymes in tears which will be an indirect criteria for assessing apoptosis. MATERIALS AND METHODS: Nitric oxide and antioxidant enzymes were estimated in tears of 25 soft contact lens wearers and compared with 25 age and sex matched controls. RESULTS: Statistically significant increase of nitric oxide (P<0.001), superoxide dismutase (P<0.001) and glutathione peroxidase (P<0.001) levels was seen in tears of contact lens wearers as compared to controls. There was also statistically significant increase in the levels of antioxidant enzymes, superoxide dismutase (P<0.05) and glutathione peroxidase (P<0.01), with increase in the total duration of contact lens wear in years. CONCLUSIONS: Increase in the level of nitric oxide and antioxidant enzymes in tears of contact lens wearers suggested that contact lens wear suppresses the process of apoptosis. However, it was also postulated that the increased levels of nitric oxide balances the anti-apoptotic activities of increased levels of antioxidant enzymes by its pro-apoptotic activity leading to protective outcomes in contact lens wearers.

Limbal stem cell study in contact lens wearers.

The effect of soft contact lens on the limbal stem cells was assessed in 30 contact lens wearers, 19 controls, and 17 cases known to cause limbal stem cell deficiency. Different results were seen as compared to controls in all the four quadrants, but more severe in cases known to cause limbal stem cell deficiency.

Are high-water-content contact lenses safe?

We examined the role of tear secretion on contact lens water content during selection. Tear secretion was estimated using Schirmer's tests. High-water-content contact lenses compromised the tear film more than low-water-content contact lenses, hence they should not be advised in low or marginal Schirmer's test cases.

Role of malondialdehyde and superoxide dismutase in cataractogenesis.

Malondialdehyde (MDA) and superoxide dismutase (SOD) in lens and plasma of patients with age-related and myopic cataract were assessed. Higher levels of lens MDA in myopic patients showed a greater lipid peroxidation process than in patients with age-related cataract indicating higher oxidative stress in myopic lens. The difference in plasma MDA of myopic cataract and age-related cataract patients was not significant. The SOD level was lower in myopic patients than in patients with age-related cataract.

Corneal and conjunctival impression cytology in soft contact lens wearers.

This study assessed changes in corneal and conjunctional cytology in 25 soft contact lens (CL) wearers and compared them with matched controls. We found 80% of grade IV keratinization in CL users for more than 7 years. Keratinization was directly proportional to duration of CL use. Conjunctival cytological changes worsened with decreasing pH, whereas corneal keratinization showed no significant correlation.

Tear film break-up time in contact lens wearers.

The increasing number of people who wear contact lenses for longer times comfortably while achieving good vision has been attributed to advances in plastics technology. Contact lenses are now worn by any adventurous ametropic patient whose vision is capable of optical improvement. This study was planned to observe the effect of gas-permeable and hard contact lenses with the following objectives: (1) to see whether there is any effect on the tear film break-up time with the different lenses; (2) to study the effect of the blink rate, if any; and (3) to examine the change in the width of the palpebral fissure. We found that only the type of lens affected the tear film break-up time and recommend that gas-permeable lenses be preferred. Any change in the blink rate should be taken as an indication of a poor fit.

Role of the indigenous drug saptamrita lauha in hemorrhagic retinopathies.

A clinical study was done on 48 eyes to assess the role of an indigenous drug, Saptamrita Lauha, in the absorption of hemorrhages and prevention of their recurrence in retinopathic eyes. Rapid absorption of retinal hemorrhages was observed in both treated groups: diabetic and hypertensive (mean durations, 16 days and 17.83 days, respectively). In three eyes, the hemorrhage cleared completely; partial clearance was observed in the rest of the eyes. Recurrence of a hemorrhagic episode was less in treated eyes (25% in each group) compared with control eyes (60% in diabetic and 50% in hypertensive patients). This study suggests that Saptamrita Lauha may hasten the process of retinal hemorrhage absorption and prevent its recurrence. The beneficial effect could be attributed to the flavanoid-like properties of one of the ingredients of this natural product.

Senile cataract and glucose-6-phosphate dehydrogenase deficiency in Indians.

Erythrocytic glucose-6-phosphate dehydrogenase (G-6-PD) was tested in 163 cases of senile cataract and 79 age- and sex-matched controls. There was no statistically significant difference between the overall incidence of G-6-PD deficiency in cataract in comparison to controls. However, amongst the cataract patients the frequency of G-6-PD deficiency was significantly higher in the age group 40 to 50 years (12.1%) as compared to those aged 51 years or more.

Association of hypomagnesemia with diabetic retinopathy.

Serum magnesium was measured in 100 patients of type II diabetes mellitus (40 without retinopathy, 40 with non-proliferative and 20 with proliferative retinopathy) without malnutrition, hepatic or renal disease or albuminuria and in 100 age and sex matched controls. The serum magnesium levels were lower in diabetics than in controls (P less than 0.001), and the levels in diabetics with non-proliferative and proliferative retinopathy were significantly lower than in those without retinopathy (P less than 0.001). These data seem to point towards an association between hypomagnesemia and diabetic retinopathy.

Catecholamines in diabetic retinopathy.

An attempt has been made to correlate the catecholamines and diabetic retinopathy. Plasma catecholamines and their urinary metabolite, vanillylmandelic acid, were measured in 53 cases of different stages of diabetic retinopathy and the results compared with the 30 cases of the control group. The study revealed a rise in total plasma catecholamines that was significant in the preretinopathic stage and highly significant in the early as well as in the late stages of diabetic retinopathy. Thus, catecholamines may play an important role in the pathogenesis of diabetic retinopathy by stimulating the counterregulatory hormones, namely growth hormone and glucagon.

Corneal curvature and trachoma.

In a study of 141 cases in different stages of trachoma, a definite change was observed in the curvature of upper part of cornea, which had become ectatic. The difference in curvature depended on the stage and severity of the trachoma. Most of the patients had fourth stage trachoma. Also, the degree of ectasia was greatest in the late stages of the disease--a point that must be kept in mind when lamellar keratoplasty is done in this type of case.

Cortisol in diabetic retinopathy.

Plasma cortisol levels and its metabolite-17-hydroxycorticosteroids from the urine of 53 patients were evaluated. These 53 patients had early and late stages of diabetic retinopathy. Values were compared with 30 cases of a control group. Plasma cortisol was found to be raised significantly in early as well as in advanced stages of retinopathy, while 17-hydroxycorticosteroid was significantly raised in earlier stages of diabetic retinopathy only. The findings suggest that increased plasma cortisol levels may take some part in the production of diabetic retinopathy.

Conductivity and hardness changes in aged compacts.

Batches of sodium, potassium, and ammonium chloride tablets containing no excipients and spray-dried lactose tablets containing 0.5% magnesium stearate were stored at 20 and 76% relative humidity. Electrical resistance and hardness measurements were made within 1 hr after compression and at intervals during a 45-day period. Hardness values of sodium, potassium, and ammonium chloride tablets stored at 20% relative humidity increased from 70 to 200% at 45 days, while conductances decreased 10-fold. Tablets stored at 76% relative humidity showed no increases or slight decreases in hardness with slight increases in conductance. Lactose tablets decreased slightly in hardness with corresponding increases in conductance.

Electrical conductance of directly compressible materials under pressure.

An electrometer that allowed direct recording of resistance changes during compression was used to measure the conductances of sodium chloride, potassium chloride, ammonium chloride, and sodium citrate. The effects of initial particle size, lubricant level, moisture content, and compaction pressure were determined. Direct compression tableting diluents also studied were dextrose, sucrose, lactose, microcrystalline cellulose, and dibasic calcium phosphate. Distinctive conductance patterns were observed and are rationalized in terms of previously proposed bondign machanisms.

Effect of intraocular surgery on the tension of the other eye: preliminary report.

Thirty-one cases of glaucoma and cataract were studied to determine if intraocular surgery in one eye could affect the ocular tension in the fellow eye. Twenty-seven patients showed varying degrees of change in the untreated eye. Possible factors causing the change have been discussed.

Lysozyme in corneal ulcer.

In the present experimental study the role of lysozyme drops in healing of corneal ulcer of staphylococcal origin (sensitive to chloramphenicol) was studied on 16 albino rabbits. In 8 rabbits, in one eye placibo drops (distilled water) and in the other eye lysozyme 1% were put 4 times daily. In the other 8 rabbits, in one eye chloramphenicol drops 0.4% and in the other eye chloramphenicol drops 0.4% + lysozyme drops 1% were instilled 4 times daily. It was observed that the rate of healing of corneal ulcer was much earlier in the eyes which had local instillation of chloramphenicol drops + lysozyme in comparison to the eyes which had only chloramphenicol drops, lysozyme drops, or distilled water.