Use of refractive direct ophthalmoscopy for estimation of refractive error

The purpose of this study was to find if direct ophthalmoscopy, a simple technique, could be used to give an approximate value of the refractive correction for a patient. This would shorten the time and lessen the effort to be expended during the following retinoscopic examination done for finding the patient's refractive correction. The use of direct ophthalmoscopy for this specific purpose is especially desirable where retinoscopic examination is quite tedious, e.g. uncooperative patients like children, bed-ridden patients and mentally retarded subjects, in patients with a large central corneal opacity and in patients having a large refractive error. The study was divided into two phases. In phase I, refractive direct ophthalmoscopy followed by classical retinoscopy was done for 92 subjects (184 eyes) in the age group of 11-35 years. The method of regression analysis was used to find a regression equation relating the readings to refractive error determined by the two above techniques. In phase II of study, the refractive correction needed for 50 other subjects in the similar age group was estimated using this regression equation by inserting their respective direct ophthalmoscopy readings. Then, these estimated values and classical retinoscopic examination values were compared. The refractive error determined after retinoscopy and that derived from regression equation (incorporating direct ophthalmoscopy readings) was statistically comparable (t = 0.52, p = 0.60). The correlation coefficient (r value) between the two methods was 0.37. Direct ophthalmoscopic lens reading can be used to give a fairly accurate estimate of refractive error in a patient's eye by using a linear regression equation, which relates these two examination techniques. The magnitude of astigmatic error, however, cannot be obtained.

Efficacy and safety of brimonidine, dorzolamide and latanoprost as adjunctive therapy in primary open angle glaucoma

A double-blind, randomised, controlled trial was carried out to evaluate the efficacy and safety of brimonidine, dorzolamide and latanoprost as an adjunctive therapy in patients with primary open angle glaucoma (POAG). A total of 200 males and 72 females with POAG uncontrolled with previous glaucoma therapy were randomly allocated to receive topical brimonidine 0.2% b.d. (n = 90), topical dorzolamide 2% b.d. (n=91) or topical latanoprost 0.005% o.d. (n = 91). One year post treatment, the mean percentage reduction in intraocular pressure (IOP) between the three groups was statistically significant (p < 0.0001). In an intergroup comparison of efficacy, there was a statistically significant difference between the brimonidine and dorzolamide groups (p = 0.018) and between the dorzolamide and latanoprost groups (p = 0.76) but the efficacy of brimonidine was not significantly higher than latanoprost in the brimonidine and latanoprost groups (p = 0.002). Patients experiencing mild to severe side-effects were statistically similar in the three groups. On an inter-drug comparison of side-effects, we found no statistically significant difference in the brimonidine and latanoprost groups (p = 0.25); and the brimonidine and dorzolamide groups (p = 0.067), while the number of side-effects with latanoprost was significantly higher in the dorzolamide and latanoprost groups (p<0.003). All three drugs caused a significant reduction in the mean IOP from pretreatment values. The brimonidine group had a higher number of patients experiencing severe side-effects necessitating alteration of therapy.

Normal values for inner intercanthal, interpupillary, and outer intercanthal distances in the Indian population

The purpose of this study was to establish a set of normal values for inner intercanthal distance (IICD), interpupillary distance (IPD) and outer intercanthal distance (OICD) in a normal Indian population aged 3-80 years and to find whether the difference between the values of these parameters is statistically significant. We also aimed to compute a regression equation for calculating these. Two thousand five hundred clinically normal Indians were enrolled in the study. A millimeter scale was used to measure IPD and IICD. OICD was measured from the bar reading of Hertel's exophthalmometer. Statistical methods were used to calculate the mean and standard deviation values for these parameters. T-test was applied to determine whether difference between the mean values for these parameters in both sexes was statistically significant or not. A regression equation was also computed to find the values for these parameters in both sexes. The IICD, IPD and OICD ranges for males were 20-36 mm, 46-70 mm and 76-105 mm, and for females 20-36 mm, 46-75 mm and 71-105 mm, respectively The difference between the mean values for these parameters was statistically significant in some age groups but not in others. Gender did not usually influence the normal values for IICD, IPD and OICD in the Indian population. The normal values of these parameters were usually lower than those observed for other races. A knowledge of normal values in this population subgroup can help in studying orbito-cranial growth patterns, syndrome diagnosis, surgical management of cranio-facial deformities and trauma, and manufacture of spectacles.

Methanol-induced optic neuropathy: treatment with intravenous high dose steroids

The aim of this study was to find the potential benefit of intravenous high dose steroids in the treatment of patients with methanol optic neuropathy. Four patients complaining of diminution of vision after taking methylated spirit presented to us within a variable period of its consumption. The systemic features of methanol poisoning were absent in these patients. Raised blood levels of methanol confirmed the diagnosis of methanol optic neuropathy. All these patients received high doses of intravenous steroids for three days, followed by oral steroids, 1 mg/kg body weight, for 11 days. The administration of high doses of intravenous steroids led to an improvement of visual status in all four patients. Intravenous high dose steroids benefit the visual status of patients with methanol-induced optic neuropathy, provided the interval between the consumption of methanol and starting treatment is short. Further studies should be undertaken to document the role of intravenous steroids in this context.

Presentations of cranial nerve involvement in two patients with Herpes zoster ophthalmicus

Two cases of Herpes zoster ophthalmicus complicated by motor nerve palsies are being reported. The investigations ruled out other diseases which can affect ocular motor nerves, e.g., diabetes, hypertension, syphilis and malignancy. The cases are being reported because of the rare presentations of Herpes zoster ophthalmicus like isolated internal ophthalmoplegia and VI nerve palsy in Case-1 and absence of iritis with third nerve involvement in Case-2. The probable etiology for occurrence of these uncommon phenomena has been postulated.