Martha Motuz Leen

Long-term Survival of Molteno Glaucoma Drainage Devices

PURPOSE To evaluate the long-term outcome of the Molteno implant drainage device using survival analysis. METHODS A retrospective chart review was performed on 77 eyes of 71 patients that underwent Molteno implantation for intractable glaucoma unresponsive to conventional management from October 1984 to April 1990 at the University of Washington Eye Center and had at least 6 months of follow-up data. Success was defined as a postoperative intraocular pressure of 22 mmHg or lower with (qualified success) or without (complete success) glaucoma medications and no additional glaucoma surgery, phthisis, or loss of light perception. RESULTS The median follow-up was 44 months (range, 6-107 months). Indications for Molteno implantation were aphakia/pseudophakia (n=24), neovascular glaucoma (n=20), uveitic glaucoma (n=12), failed trabeculectomy (n=9), traumatic glaucoma (n=8), and congenital glaucoma (n=4). The total success was 57% (23% complete; 34% qualified) at the last follow-up. Kaplan-Meier survival curves demonstrated a continuous and relatively linear attrition of success over at least 5 1/2 postoperative years. The uveitic glaucoma group had the highest success rate of 75%. Eyes with neovascular glaucoma failed significantly more frequently than those with uveitic glaucoma (P<0.01). There was no significant difference in outcome based on sex, race, single versus double plate, anterior chamber versus posterior chamber tube placement, or two-stage versus single-stage surgery. Younger age was associated with a significantly higher failure rate after controlling for glaucoma category (P<0.01). CONCLUSION The Molteno implant drainage device offers a reasonable long- term outcome in eyes with intractable glaucomas. However, an ongoing rate of failure, not unlike that seen after other filtration surgery, is to be expected.

Vitrectomy for Ciliary Block (malignant) Glaucoma

BACKGROUND Ciliary block (malignant) glaucoma is a rare surgical complication occurring in patients with pre-existing glaucoma. Misdirected aqueous fluid causes forward movement of the lens/iris diaphragm, shallowing the central and peripheral anterior chamber. Although most patients with ciliary block respond to medical or laser therapy, those with refractory glaucoma often require pars plana vitrectomy to normalize aqueous flow. METHODS The medical records of 21 consecutive patients with refractory ciliary block glaucoma treated by pars plana vitrectomy were reviewed retrospectively to determine the efficacy of this procedure in alleviating ciliary block. Data were collected regarding anatomic characteristics of the eye, history of glaucoma, prior ocular surgery, and outcome after vitrectomy. RESULTS Pre-existing glaucoma and recent intraocular surgery were noted in all patients with ciliary block glaucoma. Of 21 eyes, 8 (38%) had undergone multiple prior intraocular surgeries. The initial pars plana vitrectomy was successful in alleviating ciliary block in 14 (70%) of 20 eyes. Of those six eyes that failed to improve after initial vitrectomy, five (83%) were phakic. Additional vitrectomy surgery to relieve ciliary block was required in three (60%) of five phakic patients who failed initial vitrectomy. Complications during the treatment of ciliary block included cataract formation, retinal detachment, bleb failure, and serous choroidal detachment. CONCLUSIONS Pars plana vitrectomy is a useful adjunct to therapy for ciliary block glaucoma when medical and laser treatment fail to alleviate the process. Surgically removing the anterior hyaloid to re-establish normal aqueous flow constitutes the primary goal of surgery. In some cases, surgery is compromised by poor visualization of the anterior hyaloid, avoiding glaucoma filtration sites, and guarding against damage to the crystalline lens.

Glaucoma screening using the scanning laser polarimeter.

Purpose: To determine the ability of scanning laser polarimetry (GDx Nerve Fiber Analyzer; Laser Diagnostic Technologies, Inc., San Diego, CA) to separate normal eyes and those considered likely to have glaucoma in a public glaucoma screening. Methods: A 2‐day public glaucoma screening program was held at two different institutions. Each subject underwent ophthalmologic examination, Humphrey perimetry (24–2 Fastpac program), and imaging using scanning laser polarimetry (GDx) in each eye for allocation into a diagnostic category: normal, ocular hypertensive, glaucoma suspect, or glaucoma. Results from the normal and glaucoma groups were analyzed, using modulation parameters calculated from a measurement band located 1.8 disc diameters from the disc, and selected parameters provided automatically by GDx software. Receiver operating characteristic curves were used to depict the sensitivity/specificity relationship at different GDx parameter cutoff levels. Results: Of 200 subjects, 197 were classified; 122 were classified as normal, 23 were classified with ocular hypertension, 30 were classified as glaucoma suspects, and 22 were classified with definite glaucoma. Three subjects had ocular diseases other than glaucoma. The maximum area under the receiver operating characteristic curve for modulation parameters was 0.935, and for the GDx software parameters was 0.901. Conclusions: Scanning laser polarimetry may be useful in glaucoma screening.

Retinal hemorrhages associated with ocular decompression after glaucoma surgery

Two cases of retinal hemorrhages in glaucomatous eyes associated with ocular decompression following glaucoma filtration surgery are presented. Both patients were young, healthy men with markedly elevated preoperative intraocular pressures (IOPs). The hemorrhages were blot shaped and scattered throughout the macula (including the fovea) in each eye that underwent surgery. One eye had hemorrhages with distinct white centers. Each eye that underwent surgery experienced a permanent decrease in visual acuity after resolution of the hemorrhages. A gradual decrease of IOP preoperatively and intraoperatively is recommended in order to avoid this complication.

Digital Palpation of Intraocular Pressure

BACKGROUND AND OBJECTIVE Previous studies investigating the accuracy of digital palpation through the eyelids to estimate intraocular pressure (IOP) have shown disappointing results. In this study, the accuracy of digital assessment of IOP by palpation of the bare cornea is investigated. MATERIALS AND METHODS The IOP of a cadaveric eye model was varied from 5 to 40 mm Hg in increments of 5 mm Hg. Two examiners, one experienced and one inexperienced, digitally palpated the corneas and estimated IOP. The results were compared before and after a 1-hour training session. RESULTS Prior to the training session, the experienced examiner guessed correctly 46% of the time and was correct within 5 mm Hg 100% of the time. The inexperienced examiner guessed correctly 21% of the time and was within 5 mm Hg 62% of the time. After the training session, the experienced examiners score did not significantly (38% correct, 88% within 5 mm Hg, P = .05. CONCLUSIONS Digital assessment of IOP by palpation of bare cornea is accurate when performed by experienced individuals. A minimal amount of training using the eye model may improve ones accuracy.

Probability maps of sequential Glaucoma-Scope images help identify significant change

PurposeThe purpose of this study was to identify areas of the optic disc showing high variability of repeated depth measurements, and to minimize the effect of baseline variability in interpretation of possible change over time using the Glaucoma-Scope. MethodsSeventy-four eyes from 70 subjects were analyzed with the Glaucoma-Scope. Three images were obtained on each of two separate sessions during the same day. At each location, the mean depth of the three images for each session was calculated to create a “baseline image.” A contour map of standard deviation (SD) values at each topographic location was created for each subject reflecting local variability at different parts of the disc. The contour map and disc photograph were compared to determine what photographic features predicted high variability. A modified two-sample t-test was used at each topographic location to obtain p-values for the likelihood that a difference in mean depth between sessions was attributable to measurement variability alone. ResultsContour plots of SD for most subject eyes showed high variability in steeply sloped areas of the disc and along large blood vessels, with low variability near the cup center. The use of probability plots for significance of depth changes between test sessions automatically accounted for increased pointwise variability. The proportion of topographic locations showing statistically significant change but attributable to chance variation when no true change has occurred approximated the predicted proportion based on our modified t-test model. ConclusionA contour map of standard deviations of depth based on Glaucoma-Scope baseline images can identify areas of the disc with high variability. Statistical methods such as probability maps that account for local variability in the baseline image may be helpful in distinguishing true change from artefactual change over time.

Detection of Optic Disc Changes with Glaucoma-Scope Probability Maps

PurposeTo test whether a statistical method using a probability map could detect true changes in optic disc topography. MethodsThe average of three Glaucoma-Scope images (Ophthalmic Imaging Systems were used for analysis at each of two sessions. A Glaucoma-Scope probability map was constructed for each eye using statistical methods. The proportion of topographic locations with p values less than 0.05 on a modified two-sample t test (p-proportion) and the difference in the mean position of the disc (MPD) from two imaging sessions were calculated. Two pairs of stereoscopic disc photographs for 43 eyes with longitudinal follow-up were evaluated for change by four experienced glaucoma specialists masked to patient clinical information. Clinical change was considered to have occurred when the assessments of at least three of the four specialists were agreed on. The cutoff values for p-proportion and change in MPD that provided 95% specificity were calculated using a separate sample of 69 subjects who had serial images taken at two separate sessions on the same day, and thus showed no clinical change in the optic disc. ResultsThe cutoff values of 95% specificity for the p-proportion and the change in MPD were 18% and 25.1 μm, respectively. Of 43 eyes with longitudinal follow-up, 14 showed definite clinical change. Sensitivity of the p-proportion and change in MPD for detecting this change was 100% and 85.7%, respectively. For all 43 patients with longitudinal follow-up, the percent change in intraocular pressure (IOP) correlated strongly with both the p-proportion and the change in MPD. ConclusionUsing data obtained with the Glaucoma-Scope, a statistical method based on probability mapping can be used to detect true changes in disc topography. The p-proportion was more sensitive than change in MPD in detecting clinical change in the study eyes. This statistical methodology may also be applicable for interpretation of data obtained with other optic disc analyzers.

Prevention and management of hypotony after glaucoma surgery.

Postoperative hypotony is a common complication of glaucoma filtering surgery, particularly with adjunctive use of antifibrotic agents. Associated structural sequelae and reduced visual function may occur in some eyes, resulting in the low-pressure syndrome. Precautions may be taken intraoperatively and postoperatively to decrease the likelihood of hypotony. Sometimes, despite these measures, the low-pressure syndrome still can occur, the management of which can be difficult. When simple observation does not result in spontaneous resolution, several noninvasive and invasive techniques are available, targeted at the cause of low IOP.