Ischaemic optic neuropathy is of two types: anterior (AION) and posterior (PION), the first involving the optic nerve head (ONH) and the second, the rest of the optic nerve. Pathogenetically AION and PION are very different diseases. AION represents an acute ischaemic disorder of the ONH supplied by the posterior ciliary artery (PCA), while PION has no specific location in the posterior part of the optic nerve and does not represent an ischaemic disorder of any definite artery. The most important step towards a logical understanding of the underlying causes, clinical features, pathogenesis and rational management of AION, is to understand the basic scientific issues involved; these are discussed in some detail. AION clinically is of two types: (1) that due to giant cell arteritis (arteritic AION: A-AION) and (2) non-arteritic AION (NA-AION). NA-AION, the more common of the two, is one of the most prevalent and visually crippling diseases in the middle-aged and elderly, and is potentially bilateral. NA-AION is a multifactorial disease, with many risk factors collectively contributing to its development. Although there is no known treatment for NA-AION, reduction of risk factors is important in decreasing chances of involvement of the second eye and of further episodes. Our studies have suggested that nocturnal arterial hypotension is an important risk factor for the development and progression of NA-AION. The role of nocturnal arterial hypotension in the pathogenesis of NA-AION and management of nocturnal hypotension is discussed. Potent antihypertensive drugs, when used aggressively and/or given at bedtime, are emerging as an important risk factor for nocturnal hypotension, and there is some evidence that NA-AION may be occurring as an iatrogenic disease in some individuals. A-AION, by contrast, is an ocular emergency and requires immediate treatment with systemic corticosteroids to prevent further visual loss. The clinical parameters which help to differentiate the two types of AION, and their respective management are discussed.

Purpose: 1.To determine the anatomical site and underlying causes of severe visual impairment and blindness in children in special education in Andhra Pradesh, India. 2. To compare the causes of blindness in two different regions in the state. 3. To evaluate improvement with correction of refractive error and low-vision devices (LVDs) Methods: Children in 6 schools for the blind and in 3 integrated education programmes were examined by one ophthalmologist, and were refracted and assessed for LVDs by an optometrist. The major anatomical site and underlying aetiology of severe visual impairment and blindness (SVI/BL; <6/60 in the better eye) were recorded using the standardised WHO reporting form. Results: Two hundred and ninety one students under 16 years were examined, and after refraction, 267 (91.7%) were classified as being severely visually impaired or blind. The most common anatomical sites of SVI/BL were retina in 31.1% children; cornea in 24.3%; and whole globe in 20.2%. The aetiology was unknown in 38.2%, hereditary in 34.8% and childhood causes in 24%. 114 children (39.2%) had functional low vision (i.e. visual acuity <6/18 to light perception with navigational vision). In this group, 36 children improved with spectacles and 16 benefited by LVDs. 41 children (15.4%) were able to read N10 point though they were studying Braille. Conclusion: Overall 37.4% of children had "avoidable" causes of blindness. The major avoidable causes were vitamin-A deficiency and cataract. Vitamin-A deficiency and congenital anomalies were more common in the dry plateau areas of the state. One in seven children could read normal print with optical support.

Purpose:To obtain data on the characteristics of low-vision patients seen at a tertiary eye care hospital in India. Methods:Records of 410 patients were retrospectively reviewed at the Centre for Sight Enhancement, L.V.Prasad Eye Institute, Hyderabad, India. Patients underwent a comprehensive clinical low-vision examination. Data obtained included age, gender, consangunity, visual acuity, visual fields, ocular conditions causing low vision and types of low-vision devices and methods prescribed. Results:Two hundred and ninety seven (72%) of 450 patients were male. One-fifth were in the 11-20 years age group (21%). Visual acuity in the better eye was <6/18 - 6/60 in almost half these patients (49.3%). One hundred and twenty two patients (29.9%) referred with a visual acuity of ≥ 6/18, either had difficulty in reading normal print or had restricted visual fields. The main causes for low vision were: retinitis pigmentosa (19%), diabetic retinopathy (13%), Macular diseases (17.7%), and degenerative myopia (9%). Visual rehabilitation was achieved using accurate correction of ametropia (174 patients), approach magnification (74 patients) and telescopes (45 patients) for recognising faces, watching television and board work. Spectacle magnifiers (187 patients), hand/stand magnifiers (9 patients), closed-circuit television (3 patients), overhead illumination lamp (143 patients) and reading stand (24 patients) were prescribed for reading tasks. Light control devices (146 patients) were used for glare control, and cane (128 patients) and flashlight (50 patients) for mobility. Patients were trained in activities to improve their daily living skills, (54 patients); counselled in environmental modification (144 patients) and ancillary care (63 patients) for educational and vocational needs. Conclusion:Data obtained from this study elucidates the characteristics of low-vision patients. This information is likely to help in the development of appropriate low vision services.

Purpose: To report the timing of retreatment and clinical outcomes in patients with a partial corneal flap during laser in-situ keratomileusis (LASIK), and to describe the causes of this complication. Methods: Retrospective review of case records of four patients (4 eyes) who had a partial corneal flap during LASIK. Results: The mean age of the four patients was 23 ± 4.7 years, and mean preoperative spherical equivalent (SE) refraction was -9.1 ± 3.1D (range, -5.5 to -13D). A 160 μm corneal flap was attempted during the initial treatment. Retreatment with a 180 μm corneal flap was performed at a mean of 5.1 ± 1.6 weeks (range, 4 to 7.5 weeks) after the initial procedure. There were no intraoperative complications during retreatment. Post-LASIK mean SE refraction was -1.0 ± 1.1D (range, +0.38 to -2.0D), after a mean follow up of 19 ± 15.7 weeks (range, 7 to 42 weeks). Best spectacle-corrected visual acuity decreased in one eye from 6/5 to 6/6 and was maintained in the others. Conclusion: LASIK retreatment can be performed as early as one month after a partial flap, if the refraction is stable and a thicker corneal flap is created.

PURPOSE: To determine whether pseudophakic astigmatism is a desirable goal, and if so, which one is better: against-the-rule (ATR) or with-the-rule (WTR). METHOD: Eyes were included only if they had an uncorrected vision > or = 6/18 and N/18. Three groups, of 40 patients each were evaluated: group 1, pseudophakes with neutral astigmatism; group 2, with ATR and group 3, with WTR astigmatism Unaided distance and near visual acuity was recorded. Statistical analysis was performed using the chi-square test for independence. RESULTS: Unaided distance vision of > or = 6/7.5 was achieved in 19 eyes (47.5%) of group 1 (neutral), 12 eyes (30%) in group 2 (ATR), and 5 eyes (12.5%) in group 3 (WTR) (p = 0.0133, significant). Unaided near vision of > or = N/9 was achieved in 17 eyes (42.5%) in group 1 (neutral), 34 eyes (85%) in group 2 (ATR), and 10 eyes (25%) in group 3 (WTR) (P < 0.001, significant). Group 1 (neutral) fared the best for unaided distance visual acuity. Group 2 (ATR) was better than in group 3 (WTR) for distant vision. Group 2 (ATR) fared the best for unaided near vision. CONCLUSION: ATR astigmatism could be a desirable goal after cataract extraction in selected populations because the largest proportion of these cases achieved good unaided near vision with acceptable distant vision.

Purpose: To describe clinical features and treatment outcomes in patients with advanced Nocardia asteroides keratitis. Methods: Retrospective review of case records of 7 patients with culture-proven Nocardia keratitis. Results: Corneal infection occurred after corneal trauma in two patients, cataract surgery in three patients, penetrating keratoplasty in one patient and was associated with a silicone buckle element infection in one patient. Mean duration of infection at presentation was 33.4 days (7-75 days), and five patients had received prior treatment with corticosteroids. Six of seven patients had deep corneal suppuration at the time of: presentation, clinically suggestive of mycotic keratitis. In two patients who had received prolonged corticosteroid therapy (≥ 45 days), the eyes could not be salvaged. Complete resolution of infection was achieved in all 4 eyes treated with topical fortified cefazolin eye drops (50mg / ml).

Purpose: To study the effect of a topical non-steroidal anti-inflammatory drug as an alternative to topical steroids for postoperative control of inflammation in cataract surgery. Methods: The effect of diclofenac sodium 0.1% following cataract surgery was studied and compared to routine corticosteroid, dexamethasone phosphate 1% in a prospective, double-blind randomized study. Both groups were similar in baseline parameters. Postoperative inflammatory response, intraocular pressure and best-corrected visual acuity following standard extracapsular cataract extraction were assessed in both groups in the initial 21 days and the severity of these parameters was graded. The severity of postoperative inflammatory response to the two drugs was graded at 1, 3, 7, 14 and 21 days. Intraocular pressure and visual acuity at baseline and endpoint were compared and statistically analyzed. Results: The two groups did not differ statistically in treatment effect for any of the variables including aqueous cells, flare, ciliary congestion, Descemet's folds, visual acuity and intraocular pressure (p< 0.001). However there seemed to be a trend towards quicker improvement with corticosteroid when cells in the anterior chamber were considered. There were no side effects from topical diclofenac, and it was well tolerated. Conclusion: Dicfofenac sodium is as effective as topical corticosteroid and can be used as an alternative in routine postoperative treatment following uncomplicated cataract surgery.

Purpose: To evaluate the efficacy of multiple combined procedure (Pentagon approach) as single-step secondary repair in cases of extensive keratolenticular trauma in paediatric age group. Methods: Retrospective evaluation of 18 patients of penetrating injuries with sclero-keratolenticular trauma, who underwent multiple procedure as single-step secondary repair by a single team of two surgeons during a 4 year period. Surgical procedure included reconstruction of anterior segment, synechiolysis, excision of membrane, lensectomy, open sky vitrectomy, PC IOL implantation over frill and penetrating keratoplasty. Meticulous antiamblyopia measures were applied in all cases. Results: Extensive vasoproliferative membrane, complicated cataract and anterior vitreous condensation were significant intra-operative hurdles. Moderate uveitis, secondary glaucoma, persistent epithelial defects were problems noted. Eleven (61.22%) patients attained good visual outcome. Regrafting was required in remaining cases due to delayed graft failure. Conclusion: Despite being a highly complex technique, Pentagon approach provides effective management profile in terms of graft success and functional outcome, especially in keratolenticular trauma, in children.

Information technology has had a tremendous impact on the outlook of our professional lives. The Internet has revolutionised the speed of access to information with touch of a button. This article discusses the various aspects of information technology which are changing and enhancing our professional lives. It provides tips to enable the busy practising clinician to use the available resources effectively. Problems such as reliability of information on the web and how to assess the quality of such matter are also discussed.

Knowledge and the usage of actual sample size formulae are a necessity as validity of the inferences from research studies is often dependent on this. This paper explains how sample sizes are calculated. The concept of sampling variation is explained to emphasize the need for its proper calculation. Sample size formulae are explained with examples to provide researchers with a means of calculating the sample sizes for the commonly used study designs. Ophthalmic data are used as examples. It is perceived that this will improve the quality of inferences drawn from ophthalmic research studies.