Closure of leaking filtering blebs with cyanoacrylate tissue adhesive

Five leaking filtering blebs, occurring between 10 months and 21 years after trabeculectomy, were closed with cyanoacrylate tissue adhesive. Filtering bleb integrity was preserved in four cases, so that additional microsurgery was avoided. The only problem associated with use of tissue adhesive was the development of corneal abrasions in three cases. Although it is an accepted treatment for these conjunctival fistulas, only nine previous cases have been reported to our knowledge. We strongly recommend the use of tissue adhesive as a presurgical treatment in the management of leaking filtering blebs which present as a late postoperative complication of glaucoma surgery.

Chronic reversal of hemifield loss after intraocular pressure lowering in advanced glaucoma

Lowering intraocular pressure in two cases of severe glaucoma was associated with a chronic reversal of hemifield loss, as documented by automated threshold perimetry. In the first case, a small central 10 degrees island of vision expanded to 40 degrees in both hemifields eight months after intraocular pressure lowering by filtration surgery. The mean deviation of the central 30 degrees field improved by more than 14dB or 1.4 log units. To our knowledge, this case represents the greatest degree of reversal of chronic visual field loss reported in the literature. In the second case, a small central 10 degrees island of vision slowly expanded to 40 degrees in the inferior hemifield over a three-year period.

Use of a central 10 degrees field and size V stimulus to evaluate and monitor small central islands of vision in end stage glaucoma

In a retrospective review of 24 clinically stable eyes with small central islands of vision due to end stage glaucoma the combined use of a central 10 degrees program and size V stimulus (10-2 with V) measured visual function undetected on a central 30 degrees field tested with both the standard size III and non-standard size V stimuli. Furthermore, the mean sensitivity of the 10-2 with V remained stable on serial field testing (mean 3.9 examinations) on long term follow-up (mean 22.2 months). This study suggests that in end stage glaucoma the size V target is the stimulus of choice and a central 10 degrees field may be the program of choice of evaluating and monitoring small central islands of vision.

Detecting early glaucomatous field defects with the size I stimulus and Statpac

The influence of stimulus size and normal database on the detection of visual field defects in automated static threshold perimetry (Humphrey Field Analyzer) was investigated in 82 eyes having a diagnosis of normal, glaucoma suspect, or early glaucoma. Using a mathematically derived 'normal' database, which assumes constantly decreasing threshold sensitivities with increasing eccentricity, the size I stimulus showed significantly greater sensitivity than the size III stimulus for detecting small, shallow scotomata in the central visual field. The use of Statpac, which contains an empirically derived, age-related normal database, increased the sensitivity significantly over that of the size III stimulus (with its mathematical model), and to a degree similar to that of the size I stimulus. The results obtained with the size I stimulus were reproducible and independent of the patient's age. This study suggests a potential role for the size I stimulus in evaluating eyes having or at risk of developing early glaucomatous field loss.

Normal gray scale displays in the presence of arcuate scotomas in automated threshold perimetry

In 2.4% of visual fields and 10.4% of eyes with well-established early glaucoma, a normal gray-scale display was present despite an arcuate scotoma on pattern-deviation display in the same central threshold visual-field printout (30-2 single-field analysis program, Humphrey Field Analyzer). Also, the pattern-deviation probability plot highlighted the presence and significance of the arcuate scotoma. To my knowledge these findings have not been previously reported in the literature. In suspected glaucoma or early glaucoma, visual-field analysis based on the gray-scale display alone can be misinterpreted. In this population, the defect-depth or pattern-deviation displays should be examined before any diagnostic or therapeutic decision is made.

Lens rim artifact in automated threshold perimetry

In central static threshold visual fields (Humphrey 30-2 Program) performed with a corrective lens, lens rim artifact (LRA) was present in 10.4% of 704 fields examined retrospectively and 6.2% of 276 fields evaluated prospectively. Lens rim artifact most commonly presented as a combination of absolute and relative defects involving the temporal quadrant either alone or in combination with another quadrant. Lens rim artifact was related to seven different types of interpretational errors, five of which led to an overdiagnosis and two to an underdiagnosis. Risk factors for the occurrence of LRA include older age, high hyperopic correction, and location specific involvement probably due to a limitation in perimeter design. Field defects involving only the four targets at 27 degrees eccentricity in the temporal quadrant were due only to LRA in this series and may be disregarded when interpreting the Humphrey 30-2 Program. Recommendations are made toward minimizing the occurrence of LRA and avoiding interpretational errors associated with LRA.

Acquired epimacular membrane after multiple intraocular procedures in an infant

At 7 months of age, an infant with Lowe's oculocerebrorenal syndrome developed an epimacular membrane after three intraocular surgeries in the right eye. Serial fundus photographs document the membrane's appearance 6 months after lensectomy/vitrectomy for a dense cataract and 2 months after the second trabeculotomy for congenital glaucoma. Epimacular membranes are a vitreoretinal disorder found almost exclusively in adults. To the best of our knowledge, this is the first documented case of acquired preretinal macular membrane in an infant and the youngest case reported in the literature. The loss of formed vitreous and repeated deposition of blood products into the vitreous cavity may be responsible for the development of this preretinal membrane.

The effect of nitroglycerin ointment on the external ocular structures of rabbits

The toxicity of three different transdermal nitroglycerin ointments on the external ocular structures of New Zealand White rabbits was investigated. Using a randomized, double-blind protocol, both eyes of four rabbits in each of four treatment groups received 3.75 mg of either Nitrol Ointment, Nitrong Ointment, Nitro-bid Ointment, or Lacri-lube Ointment twice a day for 21 days. The eyelids, palpebral and bulbar conjunctiva, cornea, anterior chamber, and iris were evaluated by slit lamp. Pupillary size was noted and intraocular pressure was measured with an applanation tonometer. All parameters were evaluated pretreatment and two hours after the last dose on treatment days 1, 8, 15, and 22. On days 8 and 15, all four treatment groups had evidence of mild conjunctival injection; however, only the three nitroglycerin groups had mild conjunctival chemosis. At day 22, all four treatment groups had no statistically significant evidence of toxicity to the eyelid, conjunctiva, and iris. Only Nitrong Ointment produced any corneal toxicity, a mild diffuse punctate keratopathy statistically significant only on day 22. In addition, the four treatment groups showed no change in pupil size and intraocular pressure. Transdermal nitroglycerin preparations were well tolerated by the external ocular structures of rabbits. Additional animal studies to evaluate the dosage and frequency effects on tolerance and intraocular pressure are indicated.

Facilitating patient compliance in glaucoma therapy

Noncompliance is a major problem in glaucoma therapy. The causes, forms, and sociological variables associated with noncompliance are reviewed. A comprehensive strategy to facilitate the safe and effective use of glaucoma medications is presented and discussed. This strategy combines education about the disease and its treatment, "tailoring" of the therapeutic regimen, training and reinforcement in eyedrop application, cooperation with primary care physicians, alleviating side effects, and improving doctor-patient relationships.

Topical timolol and epinephrine: biochemical actions and interactions in the rabbit eye in vivo

The effects of topical 0.5% timolol maleate and 1% or 2% levo-epinephrine hydrochloride on aqueous humor cyclic-AMP and intraocular pressure were assessed in 97 normotensive New Zealand white rabbits in vivo. The study was conducted using three experimental protocols: (A) timolol and epinephrine individually, (B) timolol and epinephrine in coadministration, and (C) timolol and epinephrine in crossover, applied either in a single dose, twice a day for two days, and/or twice a day for six days. These studies demonstrated that timolol has complex biochemical actions, one of which is beta-adrenergic antagonism. By itself, timolol had no effect on cyclic-AMP levels. However, when used in both single-dose coadministration and in pretreatment in six-day crossover with epinephrine, it significantly diminished the cyclic-AMP elevation produced by a single dose of epinephrine. In the six-day crossover protocol, pretreatment with timolol also significantly reduced the ocular hypotensive effect of a single dose of epinephrine, thereby correlating biochemical cause with clinical effect. Yet, timolol alone had no ocular hypotensive effect. Therefore, timolol's biochemical actions in this animal model cannot explain its marked clinical efficacy in man, which appears to depend on more complex pharmacologic actions.

Inhibition of secondary cataracts by cryolysis of lens epithelium in rabbits

In an attempt to inhibit secondary cataract formation by destroying the subcapsular lens epithelium, a defined amount of freeze was applied to the anterior capsule of one eye of 16 New Zealand white rabbits just prior to a planned extracapsular cataract extraction of both eyes using phacofragmentation. The rabbits were sacrificed eight weeks after surgery and the secondary cataracts were dissected from the eyes. The degree of secondary cataract formation was evaluated by two independent observers and grading systems. Overall, 14 of 16 rabbits, or 88%, had a significant (P less than .01) reduction of secondary cataract in the treated eye as compared to the control eye. This study demonstrates that freezing of the subcapsular lens epithelium prior to a planned extracapsular cataract extraction in rabbits can significantly diminish secondary cataract formation. However because of the present difficulty in controlling the extent of the freeze to the surrounding ocular tissues with current cryoprobes, this procedure is not yet applicable in humans.