Intraoperative tremor monitoring for vitreoretinal microsurgery.

An instrument for intraoperative sensing of surgeons' hand tremor during vitreoretinal microsurgery has been developed. The instrument uses inertial sensing to detect tremor in six degrees of freedom. Instrument tip velocity is computed using the sensor data. The displacement amplitude of the tremor is then approximated analytically by modeling the velocity as sinusoidal. The instrument presently estimates oscillations at physiological tremor frequencies with error of less than 7%.

3-D position measurement for microsurgical evaluation.

A compact system for high-resolution three-dimensional measurement of microsurgical instrument tip position in the laboratory is under development. The system is useful for quantification of tremor, wander, and drift, as well as for other studies characterizing surgeons' motion in microsurgery, and for evaluation of engineered devices for enhancement of microsurgical positioning accuracy. Preliminary results are presented.

Evaluation of visual function following argon laser photocoagulation in central serous retinopathy.

The authors of previous studies on the role of photocoagulation for central serous chorioretinopathy (CSR) have based their deductions on the premise that a Snellen visual acuity of 6/6 is the end point of recovery. It is now known that patients with a visual acuity of 6/6 may have defective contrast sensitivity indicative of a visual function deficit. The present study was a prospective, controlled, and randomized evaluation of patients suffering from their first attack of CSR, in which contrast sensitivity was used to determine the effectiveness of argon laser photocoagulation as compared with more conservative treatment. Although long-term studies are necessary, the results of this study showed that while photocoagulation increases the rate of recovery for visual acuity, it is also linked with significant loss and slower recovery of contrast sensitivity.

Contrast sensitivity in diabetic retinopathy after panretinal photocoagulation.

Reports of changes in contrast sensitivity in proliferative diabetic retinopathy (PDR) patients after panretinal photocoagulation (PRP) have considered only relatively short-term results, and these have been conflicting. We evaluated contrast sensitivity changes in 30 eyes of 29 PDR patients after PRP. The patients were divided into two groups. One, group A, received PRP at one sitting, and the other, group B, at two sittings. Before and at regular intervals after PRP, all of the patients underwent a battery of macular function tests for best-corrected visual acuity, color vision, contrast sensitivity, and photostress. Contrast sensitivity was significantly affected (P < .001) in both groups immediately after PRP, but stabilized to prelaser levels by the end of 3 months. Color-vision-error scores also were significantly higher (P < .001) immediately after PRP. Best-corrected Snellen visual acuity, however, remained stable at prelaser levels. Contrast sensitivity appears to provide a more sensitive measurement of visual acuity than the Snellen chart for monitoring foveal integrity in patients undergoing PRP.

Eye casualty department.

A retrospective analysis of all new patients attending our eye casualty department was carried out during the 1 year period, from January to December 1987. During this time the casualty unit saw and treated 4905 new patients. Of these 40.61% were traumatic in origin, 30.52% comprised various ocular infections and the remaining 28.87% had miscellaneous ocular problems. On average, 13 new patients and seven consultations from other departments were seen and treated daily. Apart from the management of ocular emergencies, other functions provided by our department included glaucoma screening, donor eye collection, attending to referrals from other departments and eye health education.

Metabolic factors in the development of retinopathy of juvenile-onset type I diabetes mellitus.

Thirty-five patients of insulin-dependent diabetes mellitus (IDDM) were investigated for the effect of various metabolic factors on retinopathy. The severity of retinopathy increased with duration and age of onset of IDDM. Degree of glycaemia (fasting blood sugar, FBS) was similar in patients with or without retinopathy. All IDDM patients as a group showed severe carbohydrate intolerance with lower basal and post glucose serum immunoreactive insulin (IRI) levels and serum C-peptide radioimmunoreactivity (CPR) as compared to controls. The insulin secretory response was similar in no retinopathy, mild retinopathy and severe retinopathy groups. Patients with retinopathy had higher incidence of hyperlipidemia but mean serum levels of cholesterol and triglyceride were similar. This study does not suggest a direct relationship between the various metabolic factors studied and retinopathy due to IDDM.

Experimental inhibition of proliferative vitreoretinopathy in retinal detachment using daunorubicin.

Proliferative vitreoretinopathy (PVR) remains the most common cause of failure in retinal detachment surgery. Surgical procedures for its repair entails complex and extensive instrumentation besides technical skill. The success rate varies widely with high incidence of redetachment. Keeping this in view, we evaluated the role of intravitreal daunorubicin as an anti-mitiotic agent in the inhibition of PVR. Our study concluded that 5 micrograms of intravitreal daunorubicin effectively inhibited PVR in the rabbit eye and the dosage was safe and nontoxic. The half-life of the drug was determined to be about 140 minutes, suggesting a prolonged intravitreal concentration sufficient to prevent fibroblast proliferation.

Functional outcome of branch retinal vein occlusion after photocoagulation with various laser wavelengths--an automated perimetric analysis.

This study highlights the comparative efficacy of three different laser wavelengths--argon green, argon blue-green, and krypton red--for sector photocoagulation in fresh cases of branch retinal vein occlusion. The mean Logarithm of minimal angle of resolution (LogMAR) improved in the argon green and argon blue-green groups but decreased in the krypton red group. Statistical analysis of the automated visual fields in these eyes showed a mean change in corrected pattern standard deviation value, with increase in all three groups--minimal increase in the argon blue-green group and maximal in the krypton red group, suggesting maximum visual field defect in the krypton laser group. To conclude, the green and the blue-green wavelengths gave results that were decidedly superior to those given by krypton red: further, argon blue-green had an edge over the green wavelength.

Automated perimetric changes following panretinal photocoagulation in diabetic retinopathy.

Sixty eyes--30 with severe nonproliferative diabetic retinopathy (NPDR) and 30 with proliferative diabetic retinopathy (PDR)--underwent argon laser panretinal photocoagulation (PRP). Static perimetry (Humphrey automated visual field analyzer 630, Threshold Prog Central 30-1 and Peri 30/60-1) was done 1 day before and 6 weeks after the initial laser treatment. One day before treatment, the fields of the NPDR and PDR eyes differed mainly in the central field affection: the PDR eyes had more localized areas of markedly decreased retinal sensitivity and, therefore, a higher initial mean deviation value and higher corrected pattern standard deviation values. However, peripheral retinal sensitivity was equally depressed in the NPDR and PDR eyes. Six weeks after treatment, central retinal sensitivity had significantly improved in all of the eyes, although more so in the eyes with severe NPDR. This study suggests that static-perimetry-guided PRP is an effective treatment for diabetic retinopathy, especially severe NPDR.

Ocular ethambutol toxicity: is it reversible?

Delayed onset ocular ethambutol toxicity is usually considered to be reversible following prompt withdrawal of the drug. However, in a series of seven consecutive patients with severe visual deficit due to ethambutol toxicity, only 42.2% (3 of the 7 patients) achieved a visual recovery of better than 20/200 after an average follow-up of 8.3 +/- 2.1 months after stoppage of the drug. On fluorescein angiography, three cases (42.2%) progressed to optic atrophy during the follow-up with permanent visual damage. There were no predisposing or risk factors to contribute toward the poor visual gain. In this background, we recommend discontinuation of ethambutol from the antituberculous regimen. As an additional sidelight, the value of visually evoked potential in the monitoring of patients on ethambutol, especially in cases with early periaxial neuritis, has been emphasised.

Peribulbar anesthesia in retinal reattachment surgery.

We prospectively evaluated the effectiveness of peribulbar anesthesia in retinal reattachment surgery. Of the 24 patients studied, 2 required retrobulbar supplementation during the latter part of the surgery. Our results show that peribulbar anesthesia can be effectively used for retinal reattachment surgery and probably should be the preferred form of local anesthesia for this surgery, since the eyes involved have a relatively high incidence of axial myopia and posterior staphyloma.

Bilateral branch vein occlusion.

Bilateral branch retinal vein occlusion is a relatively rare occurrence. We report 4 patients who presented with bilateral branch retinal vein occlusion and in each of these cases the fellow eyes were involved within 6 months of the initial episode. The patients were relatively young and all of them had associated essential hypertension. The patients maintained a relatively good visual acuity through a 6-months to 1-year follow-up. This report highlights this rare entity, the associated risk factors and visual prognosis.

Sudden vision loss following retinal detachment surgery.

A 22-year-old man with Eales' disease with secondary rhegmatogenous retinal detachment with a break five disc diameters from the disc underwent radial scleral buckling using a silicone sponge episcleral explant with local cryopexy. Five hours after surgery the patient had no light perception. There was no intraoperative or postoperative rise of intraocular pressure or central retinal artery ischemia. Immediate removal of the explant brought a return of light perception and postoperative visual acuity improvement. The episcleral explant may have caused the direct optic nerve trauma that resulted in loss of vision.

Berberine, a potential drug for trachoma.

The clinical serological response to topical treatment of trachoma with Berberine an indigenous drug has been studied in 32 microbiologically confirmed cases. Efficacy of Berberine 0.2% when compared to sulfacetamide 20% was found to be superior in both the clinical course of trachoma and in achieving a fall in the serum antibody titers (P < 0.05) against chlamydia trachomatis in the treated patients.

Anti-insulin antibodies and retinopathy in juvenile onset type-1 diabetes.

Juvenile diabetics have severe loss of beta cell function and require replacement therapy with insulin. Insulin antigenicity can produce anti-insulin antibodies resulting in allergic reactions and insulin resistance. The role of insulin-anti-insulin antibody complexes in the development and progress of chronic diabetic complications like microangiopathy is not very clear. In the present study, there was statistically a significant trend of higher insulin antibody binding levels in IDDM patients who developed retinopathy. Though there was a trend of higher insulin antibody in IDDM patients with retinopathy, there was no association between insulin antibody and HLA antigen which some authors have reported.

Cryopexy in pars planitis.

Cryotherapy has been reported to be of benefit in pars planitis. We studied 16 eyes with classic pars planitis unresponsive to corticosteroid therapy. Eight eyes continued with systemic and periocular steroid therapy, and in the remaining eight eyes transconjunctival cryopexy of the peripheral retina and vitreous base was done as an additional procedure. At 6 months four of the eyes that received cryopexy showed an improvement in Snellen visual acuity, and in the other four the acuity was unchanged; none of the eyes showed any vitreous base neovascularization. Among the eyes that received steroid therapy only, the acuity was unchanged in five, improved in one and reduced in two.

Visual evoked responses in tuberculous children on ethambutol therapy.

Visual evoked responses (VERs) were recorded in 47 children, aged 3-13 years with tuberculosis, treated with ethambutol (20 mg/kg/day) as a part of the antitubercular regimen. VERs were evoked by monocular whole field stimulation, the stimulus being provided by a black and white checker-board pattern reversed every 560 msec and recorded before the commencement, 2, 4, 6, 9 and 12 months of therapy and between 3 to 6 months after stopping the drug. In the first 6 months of therapy the mean values of latency ranged from 92.8 to 101.3 msec in the 3 to less than 6 years age group and 88.5 to 100.3 msec in children 6-13 years of age. Between 6-12 months of therapy the mean values of latency were between 93.3 to 101.0 msec in the 3 to less than 6 years age group and 96.0 to 101.5 msec in the older group. Between 3-6 months after stopping therapy the means of latency ranged from 92 to 96 msec. The differences were not statistically significant at any point of time. Thus, children do not seem to be at greater risk for developing ethambutol inducted optic damage as compared to adults. Ethambutol in the above stated dose may, therefore, be recommended for inclusion in antitubercular chemotherapy in pediatrics without undue fear of subclinical toxicity.

The prevalence of microalbuminuria in diabetes: a study from north India.

Geographic/population variation in the prevalence of diabetic nephropathy is well recognised. In a study of 'native' Indians, we screened 102 non-proteinuric diabetes mellitus patients (64 NIDDM, 38 IDDM; mean age and diabetic duration 48.7 and 6.5 years, 21.6 and 6.2 years, respectively) with blood pressure less than or equal to 170/105 and without congestive heart failure, ketonuria or urinary tract infection, for the presence of microalbuminuria (albumin excretion rate greater than 20 micrograms/min). Fifty-six patients (34 NIDDM, 22 IDDM) also underwent detailed fundus examination. Seventeen NIDDM (26.6%) and 3 IDDM (7.9%) patients had microalbuminuria. Glycated hemoglobin was significantly higher in microalbuminurics in the NIDDM group (P less than 0.05). Diabetic retinopathy tended to occur more frequently in microalbuminurics (NIDDM and IDDM).