Relationship between central corneal thickness and parameters of optic nerve head topography in healthy subjects.

PURPOSE: To investigate the relationship between central corneal thickness (CCT) and topographic parameters of optic nerve head (ONH) in healthy eyes. METHODS: Right eyes of 208 healthy subjects between 40 and 59 years of age with refractive error less than 1 D were enrolled in this cross-sectional study. Ultrasonic pachymeter was used to measure CCT, and the ONH parameters were obtained by using confocal scanning laser ophthalmoscope. Relationship of various topographic parameters to age and sex were also investigated. For statistical analysis Student t test, analysis of variance, Pearson and Spearman test, and partial correlation coefficients were used. RESULTS: Mean CCT of subjects was 540.71+/-35.53 micronm (462-621 micronm), and the mean disc area was 2.37+/- 0.44 mm2 (1.28-3.66 mm2). CCT showed negative correlations to disc area, rim area, rim volume, and retinal nerve fiber layer (RNFL) area. These correlations were found to be stronger in females. Negative correlations were demonstrated between age and the mean cup depth, maximum cup depth, RNFL thickness, and RNFL cross sectional area. Women had lesser rim volumes, but bigger cup to disk (C/D) area and linear C/D ratios compared to those of men. CONCLUSIONS: In addition to its effect in the accuracy of intraocular pressure measurements, CCT has a structural relationship with the ONH in healthy nonglaucomatous eyes. Therefore, its effect on disc area might be especially important to explain the structural strength of the ONH in the pathogenesis of glaucoma.

The sensitivity and specificity of 0.5% apraclonidine in the diagnosis of oculosympathetic paresis.

AIMS: To evaluate the sensitivity and specificity of 0.5% apraclonidine test in the diagnosis of oculosympathetic paresis (OSP). METHOD: Apraclonidine (0.5%) was administered to 31 eyes, nine with a diagnosis of Horner syndrome (HS), 22 with bilateral OSP caused by diabetes, and to 54 control eyes. All were confirmed with the cocaine test. The effects on pupil diameter and upper eyelid level were observed 1 hour later. RESULTS: Apraclonidine caused a mean dilation of 2.04 mm (range 1--4.5) (p<0.001) in the pupils with OSP and it caused pupillary constriction in the control eyes with a mean change of -0.14 mm (range 0.5 to --1) (p<0.05). It caused reversal of anisocoria in all HS cases. Its effects on both pupil diameters and upper lid levels differed significantly between the groups (p<0.001). The mean elevation in the upper lid was 1.75 mm (range 1--4) in the OSP group (p<0.001) and 0.61 mm (range 0--3) in the control group (p<0.001). CONCLUSION: The effect of the apraclonidine (0.5%) test on the pupil diameter was diagnostic for OSP and had at least the same sensitivity and specificity as the cocaine test for the diagnosis of OSP.

Reversal of dysthyroid optic neuropathy following orbital fat decompression.

AIMS: To document the successful treatment of five patients with dysthyroid optic neuropathy by orbital fat decompression instead of orbital bone decompression after failed medical therapy. METHODS: Eight orbits of five patients with dysthyroid optic neuropathy were selected for orbital fat decompression as an alternative to bone removal decompression. Treatment with systemic corticosteroids and/or orbital radiotherapy was either unsuccessful or contraindicated in each case. All patients satisfied clinical indications for orbital bone decompression to reverse the optic neuropathy. High resolution computerised tomographic (CT) scans were performed in all cases and in each case showed signs of enlargement of the orbital fat compartment. As an alternative to bone decompression, orbital fat decompression was performed on all eight orbits. RESULTS: Orbital fat decompression was performed on five patients (eight orbits) with optic neuropathy. Optic neuropathy was reversed in all cases. There were no cases of postoperative diplopia, enophthalmos, globe ptosis, or anaesthesia. All patients were followed for a minimum of 1 year. CONCLUSIONS: In a subset of patients with an enlarged orbital fat compartment and in whom extraocular muscle enlargement is not the solitary cause of optic neuropathy, fat decompression is a surgical alternative to bony decompression.

A possible link between the pseudoexfoliation syndrome and coronary artery disease.

PURPOSE: This is a collaborative case-control study from Ophthalmology and Cardiology departments of a tertiary care hospital, designed to explore the relationship between coronary artery disease (CAD) and pseudoexfoliation syndrome (PEX). METHOD: In all, 50 patients with CAD proven by coronary angiography, and 50 controls with normal coronary angiographic findings were compared in terms of PEX, other vascular diseases, and retinal vascular findings. chi2-test and Student's t-test were used for statistical analysis. RESULTS: The number of patients with PEX among CAD (+) patients was substantially larger than controls. In all, 28 of 50 CAD (+) patients and only 12 of 50 CAD (-) patients had PEX. PEX was significantly associated with CAD (P=0.001). When all patients were regrouped according to the presence of PEX, patients with PEX did not differ from patients without PEX in terms of age (P=0.360) and sex (P=0.507), but the prevalence of CAD was higher (P=0.001) and fundoscopic findings of vascular diseases were significantly more prominent (P=0.0001) in PEX (+) patients. DISCUSSION: We demonstrated statistically significant difference in the prevalence of PEX in CAD patients, and also in the prevalence of CAD in PEX (+) individuals. These were striking differences. We should consider the possibility of the presence of PEX in CAD patients; and the predisposition of PEX (+) persons for CAD, which necessitates a fundus examination for findings of systemic vascular diseases.

Efficacy of levodopa and carbidopa on visual function in patients with non-arteritic anterior ischaemic optic neuropathy.

The benefit of levodopa and carbidopa therapy in improving visual function in patients with non-arteritic anterior ischaemic neuropathy (NAION) was evaluated. Twenty-four subjects with NAION were randomly selected to receive either levodopa-carbidopa or a placebo. Visual functions of neither the study nor the placebo groups showed improvement. Side effects of levodopa such as dizziness, orthostatic hypotension, vomiting and cardiac arrhythmia were seen. Levodopa and carbidopa had no therapeutic effect on visual recovery in our patients with NAION.

Visual recovery patterns in children with Leber's hereditary optic neuropathy.

Three patients with Leber's hereditary optic neuropathy (LHON) showed spontaneous improvement in visual acuities after months of legal blindness. Two male patients with bilateral subacute visual loss were 14 years of age at presentation. The first male patient had a mitochondrial DNA mutation at nucleotide position 11778. The second male patient was found to be negative for the designated primary mutations (11778, 14484, 3460) and two of the secondary mutations (15257, 9804). The third patient was a 20-year-old female who presented with bilateral optic atrophy. She had been diagnosed as LHON and was found positive for the 3460 mutation when she was 15. These patients' pattern of visual recovery by developing small islands of normal vision within a central scotoma is characteristic in such rare cases of LHON.