Management of phacolytic glaucoma: experience of 135 cases.

We retrospectively analyzed 135 eyes with phacolytic glaucoma. A trabeculectomy was added to standard cataract surgery if symptoms endured for more than seven days, or if preoperative control of intraocular pressure (IOP) with maximal medical treatment was inadequate. In the early postoperative period, IOP was significantly lower in the combined surgery group (89 eyes) compared to the cataract surgery group (46 eyes) (p < 0.001). At 6 months there was no difference in IOP or visual acuity between the two groups. There were no serious complications related to trabeculectomy. It is reasonable to conclude that in eyes with a long duration of phacolytic glaucoma, addition of a trabeculectomy to cataract surgery is safe, prevents postoperative rise in intraocular pressure and decreases the need for systemic hypotensive medications. A randomized trial is on to further address this question.

Prevalence of primary glaucoma in an urban south Indian population.

Glaucoma is fast emerging as a major cause of blindness in India. In order to estimate the prevalence of primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) in an urban South Indian population, we examined 972 individuals aged 30-60 years, chosen using a cluster sampling technique from 12 census blocks of Vellore town. They underwent a complete ocular examination, including applanation tonometry and gonioscopy, at the Medical College Hospital. Characteristic field defects on automated perimetry was a diagnostic requisite for POAG. Prevalence (95% CI) of POAG, PACG, and ocular hypertension were 4.1 (0.08-8.1), 43.2 (30.14-56.3), and 30.8 (19.8-41.9) per 1,000, respectively. All the PACG cases detected were of the chronic type. Hitherto unavailable community-based information on primary glaucoma in our study population indicates that PACG is about five times as common as POAG.

The role of artificial drainage devices in glaucoma surgery.

The use of artificial drainage devices (ADDs) or "setons" in glaucoma surgery is generally restricted to patients with refractory glaucoma at high risk for failure from conventional filtration surgery. ADDs, both valved and nonvalved are currently available in this country. Recently, some of these devices have been propogated as primary treatment even for primary glaucomas. This article examines the role of ADDs in the modern management of the glaucomas. Specific indications for ADDs and methods to reduce the complication of overfiltration are discussed. The use of antimitotics, such as 5-fluorouracil or mitomycin, with traditional filtration has decreased the indications for ADDs. The literature and our experience confirm that currently there is no role for use of ADDs as a primary procedure in most glaucomas.

Visual outcome and complications of residents learning phacoemulsification.

The increasing popularity of phacoemulsification in our country raises important training issues. We prospectively analyzed the incidence of complications and visual outcomes in the initial 70 phacoemulsifications (70 patients) performed by the first two residents learning phacoemulsification in our training programme. Both were experienced in standard (manual) extracapsular cataract extraction. Postoperative follow up of 6 weeks or longer was available in 59 eyes. The 11 patients (11 eyes) lost to follow up did not have any intra-operative complications. The overall incidence of vitreous loss was 10%, similar to the frequency of this complication (determined retrospectively) in the first 70 standard extracapsular cataract extractions performed by the same residents. Intraocular lenses (IOL) were successfully implanted in 62 eyes, as planned. One IOL dislocated into the vitreous was successfully repositioned. Other complications encountered included superior corneal edema (3 eyes), iris damage inferiorly (7 eyes) and clinical cystoid macular edema (5 eyes). A best corrected visual acuity of 6/12 or better was obtained in 56 (94.8%) of the 59 eyes available for the six week follow up. In the eyes with vitreous loss, 6 out of 7 had visual acuity better than 6/12. No nuclei were lost into the vitreous. The rate of surgical complications for residents learning phacoemulsification in a supervised manner can be acceptably low.

Evaluation of the role of syringing prior to cataract surgery.

Patients for cataract surgery in India routinely undergo preoperative syringing to rule out chronic dacryocystitis. We determined the sensitivity and specificity of the clinical test of regurgitation on pressure over the lacrimal sac (ROPLAS) as a screening test for chronic dacryocystitis and compared it to syringing. 621 consecutive outpatients who needed syringing for various reasons (including 318 who had routine syringing prior to cataract surgery) were examined in a masked manner for regurgitation on pressure over the lacrimal sac. They then underwent syringing by a trained (masked) observer. The sensitivity and specificity of ROPLAS were 93.2% and 99.3%, respectively. Using a 6.6% prevalence of chronic dacryocystitis (the prevalence in our cataract population), the negative predictive value of the test was 99.5%. In the presence of regurgitation of pressure over the sac, the high specificity of ROPLAS confirms chronic dacryocystitis. In view of the opportunity costs, when ROPLAS is negative, preoperative syringing in cataract is perhaps unnecessary, unless the findings are equivocal or the index of suspicion for chronic dacryocystitis is very high.

Confidence with confidence intervals.

When considering the results of a study that reports one treatment to be better than another, what the practicing ophthalmologist really wants to know is the magnitude of the difference between treatment groups. If this difference is large enough, we may wish to offer the new treatment to our own patients. Even in well executed studies, differences between the groups (the sample) may be due to chance alone. The "p" value is the probability that the difference observed between the groups could have occurred purely due to chance. For many ophthalmologists assessing this difference means a simple look this "p" value to convince ourselves that a statistically significant result has indeed been obtained. Unfortunately traditional interpretation of a study based on the "p" value at an arbitrary cut-off (of 0.05 or any other value) limits our ability to fully appreciate the clinical implications of the results. In this article we use simple examples to illustrate the use of "confidence intervals" in examining precision and the applicability of study results (means, proportions and their comparisons). An attempt is made to demonstrate that the use of "confidence intervals" enables more complete evaluation of study results than with the "p" value.

VISTECH contrast sensitivity testing in primary open angle glaucoma.

Contrast sensitivity has been recommended as a screening and diagnostic test in primary open angle glaucoma (POAG). We tested contrast sensitivity (CS) using Vistech charts in 184 eyes of 95 patients. Three groups were examined--established primary open angle glaucoma, glaucoma suspects and age matched controls. The distribution of contrast sensitivities amongst the three groups were similar. The median contrast sensitivity of glaucoma suspects and controls were well within normal limits while that of the POAG group fell along the lower limit of normal. In all three groups the younger subjects scored better than the older, indicating a depression of contrast sensitivity with increasing age. Even if depression of any one spatial frequency was considered abnormal, the test yielded a sensitivity of 55.4% and specificity of 69.5%. Similarly contrast sensitivity testing was found to be of little use in detecting field defects a maximum sensitivity of 47.3% and specificity of 73.3%. Vistech contrast sensitivity testing is not a useful test in POAG screening or diagnosis.

Releasable suture technique for trabeculectomy.

A retrospective review of 154 trabeculectomies with releasable sutures was performed to assess the effect of suture release on intraocular pressure (IOP) at various postoperative periods. Release of the suture was necessary in 38% of cases. The immediate reduction in IOP was significant (p < 0.01) when the suture was released during the first three postoperative weeks. Seventy percent of eyes had a reduction in IOP more than 5 mmHg if released within the first week compared to 20% after the third week. With suture release after the third postoperative week, there was no clinically significant decrease in IOP. The decrease in IOP was similar in eyes undergoing trabeculectomy alone or when cataract extraction through a separate corneal incision was undertaken simultaneously. The period during which release of suture was effective was not prolonged by use of antimetabolites. Complications included a typical windshield-wiper keratopathy (18 eyes), failure to release the suture (13 eyes), epithelial abrasion (6 eyes) and a sub-conjunctival bleed (1 eye).

Surgical magnification for intracapsular cataract surgery in a rural hospital.

Intracapsular cataract extraction is still the most common type of operation performed in India, especially in eye camps, and most of these are done without magnification. To assess the surgical outcome of intracapsular cataract surgery in a rural hospital with various magnifying systems, 121 consecutive eyes (121 patients) with uncomplicated cataract were randomly allocated to surgery with the operating microscope, binocular loupe or unaided eye. The surgery was performed by either consultants or first year residents. The best corrected vision at least four weeks post-operatively was compared among the three groups. The performance between the consultants and the junior residents was also compared. The improvement of surgical outcome with magnification was statistically significant (p = 0.0045); and clinically important with a relative risk reduction of 60.6%. The comparison between microscope and loupe magnification did not show a significant difference (p = 0.24). However, with an operating microscope, the consultants performed significantly better than the junior residents. These findings suggest that the use of magnification in intracapsular cataract extraction provides a definite advantage over an unaided eye and that the binocular loupe is a good alternative to the operating microscope in this kind of surgery.

Assessment of clinical significance: the number needed to treat.

The practising ophthalmologist is frequently confronted with treatment options shown to be "statistically significantly better" than those currently in use. Unfortunately what is statistically significant may not necessarily be clinically significant enough for the practitioner to change from the currently preferred method of treatment. In this article we use common ophthalmic examples to introduce the "number needed to treat" (NNT), as a simple clinical approach for the practising ophthalmologist wishing to assess the clinical significance of treatment options.

Practical approach to diagnosis of strabismus.

Jampolsky's approach to the diagnosis of strabismus is simple. Certain tests are to be performed in sequence to determine 1) the presence of fusion in the habitual head position under normal viewing conditions and in the primary position at near and distance; 2) the presence and characteristics of fusion vergences and 3) the deviations that exist at distance and near. These are established by the cover tests and the prism cover test. 4) Incomitance of the strabismus, A-V phenomena and mechanical weaknesses and restrictions are assessed by observations of eye movements and the forceps tests. Finally, 5) inferences about the state of the sensory system are made based on the history, vision and clinical examination. Additional tests performed on indication are the 4 diopter prism test, the prism adaptation test and the forceps muscle tests. This approach allows an accurate and reproducible examination to be performed in an objective manner making it possible to compare clinical findings over time and allow a rational plan of management to be evolved. Errors in examination arise from poor control of three factors, accommodation, fixation and fusion vergence. These can be controlled by careful attention to the test conditions. This system of diagnosis is simple to follow and understand, economic on time and altogether less of a strain to examiner (and patient) than the traditional system.