Christian P. Jonescu-Cuypers

Primary viscocanalostomy versus trabeculectomy in white patients with open-angle glaucoma: A randomized clinical trial

PURPOSE To compare viscocanalostomy, a nonpenetrating procedure for glaucoma treatment, with trabeculectomy. DESIGN Randomized controlled trial. PARTICIPANTS Twenty white subjects (20 eyes) with open-angle glaucoma with no history of surgery were enrolled. METHODS Ten subjects were randomly assigned to viscocanalostomy according to Stegmanns technique and 10 subjects to a modified Cairns trabeculectomy. A complete ophthalmologic examination was performed the day before surgery and postoperatively. Further visits were scheduled monthly for 6 to 8 months after surgery. MAIN OUTCOME MEASURES Success was defined as intraocular pressure (IOP) between 7 and 20 mmHg, with no medication. RESULTS After a mean follow-up of 6 months (range, 6-8 months), success was obtained in 5 of 10 cases in the trabeculectomy group and in no case in the viscocanalostomy group. With Kaplan-Meiers method, subjects with viscocanalostomy showed shorter postoperative IOP-reduction periods than subjects undergoing trabeculectomy. CONCLUSIONS According to the results of this short-term study, trabeculectomy was more effective than viscocanalostomy in lowering IOP in glaucomatous eyes of white patients.

Quantitative Morphologic and Functional Evaluation of the Optic Nerve Head in Chronic Open-Angle Glaucoma

Glaucoma leads to morphologic changes of the optic nerve head and to functional defects. Morphologic changes in the three-dimensional surface structure of the optic nerve head at its entrance site into the globe can be examined by laser scanning tomography. The standard technique for evaluating functional defects in glaucoma is static computerized perimetry. We compared these two techniques to determine which is more sensitive for follow-up of glaucomatous damage of the optic nerve head. If decreased function is presumed to precede imminent cell death, visual field analysis should be the more sensitive method, as cell death results in absolute defects of the visual field. However, the neuronal networks do not necessarily function in this way. In the case of loss of individual elements in the neuronal network, the complex linkages, even at the retinal level, are able to maintain functions and compensate for loss of function, which means that visual field defects would not be prominent. If the damage increases with time and is accompanied by a progressive loss of ganglion cells, however, compensation is eventually no longer possible, and the functional defects then become measurable by visual field analysis. Thus, morphologic absolute changes may be more prominent than visual field defects in the early stages of glaucoma. To evaluate the quantitative relationship between morphometrically measurable defects of the optic nerve head and measurable functional defects, we first examined the visual field with static computerized perimetry and then evaluated the surface structure with a laser scanning tomograph in 90 patients with chronic open-angle glaucoma, 10 patients with ocular hypertension, and 10 patients without any eye disease. Based on the 95th percentile of the standardized rim/disk area ratio, we calculated the relative rim area loss and correlated this with the mean defect in visual field analysis. The scatterplot shows an exponential curve. In the early stages of glaucoma, visual field defects were less prominent than morphologic absolute changes; 40% of the neuroretinal rim area is lost by glaucomatous optic nerve damage before first defects in visual field analysis appear. In late stages of glaucoma, changes in perimetry are more prominent than those observed with biomorphometry. These results show that in the follow-up of patients with early stages of glaucomatous damage, special attention should be given to morphologic absolute changes. In patients with advanced glaucoma, progress of the damage should be observed by repeated functional, rather than morphologic, examinations. It is important to keep in mind, however, that the sensitivity of any method is dependent on technology. One reason why functional tests may not be as sensitive as morphologic examination in observing patients with early stages of glaucoma may simply be that functional tests are not yet sensitive enough to detect early damage.

Ultrasound biomicroscopy and its value in predicting the long term outcome of viscocanalostomy.

Aims: To examine whether the early postoperative morphology at the site of sclerectomy, as visualised by ultrasound biomicroscopy (UBM), is an indicator of the mechanisms that lower intraocular pressure (IOP) and/or predictors of the long term outcome of viscocanalostomy. Methods: 15 eyes of 14 patients with medically uncontrolled open angle glaucoma and no history of surgery underwent viscocanalostomy according to Stegmann’s technique. Ultrasound biomicroscopy was performed during the first month after surgery. The following parameters were assessed: dimensions of the intrascleral “lake,” presence of a filtering bleb, presence of a subconjunctival cavity or a suprachoroidal hypoechoic area, and the thickness of the residual trabeculocorneal membrane. A complete ophthalmological examination was performed the day before and the day after surgery. Follow up visits were scheduled 1 week, 4 weeks, 6 months, and 12 months after surgery. Results: At 1 year successful control of IOP (<20 mm Hg) was achieved without further manipulation or medication in six of 15 eyes. The size of the intrascleral “lake” (average 0.62 mm3) did not correlate with later IOP; however, a visible route under the scleral flap and accidental perforation of the trabeculocorneal membrane were associated with long term lowering of IOP. Normal thickness of the trabeculocorneal membrane (0.10–0.15 mm) was indicative of IOP control with and without medication. When UBM showed an early collapse of the intrascleral cavity, control of IOP was not achieved. Other UBM findings did not predict long term function. Conclusion: In accordance with previous studies, the authors found that UBM examination is a useful method to evaluate outflow mechanisms after glaucoma surgery. This study shows that UBM imaging of external filtration during the early postoperative period can be used to predict the success of viscocanalostomy. However, to establish conclusively what parameters of UBM predict successful viscocanalostomy a larger number of patients must be studied.

Optic nerve head morphometry in healthy adults using confocal laser scanning tomography.

Background/aims: To study the optic nerve head (ONH) characteristics in a cross sectional study with confocal laser scanning tomography using the Heidelberg retina tomograph (HRT I) and thereby to obtain a new HRT database for comparison of healthy and glaucomatous eyes. Methods: White adults with no history of ocular pathology were eligible for the study. The examination comprised: assessment of visual acuity; slit lamp examination of the anterior and posterior segment; Goldmann applanation tonometry; computerised perimetry, and optic nerve head tomography with HRT. Eyes with ocular pathology were excluded. Mean (standard deviation, SD) and difference between right and left eye (RE–LE) were calculated for HRT I measurements. Differences in mean topographic parameters between male and female participants and between the age quartiles were analysed. The study included 1764 eyes of 882 healthy adults (154 females and 728 males, mean age of 46.8 (SD 8.6) years). The population investigated was larger and older in comparison with similar studies using confocal laser scanning tomography. Results: With HRT I, a mean disc area of 1.82 (SD 0.39) mm2, a mean cup area of 0.44 (SD 0.32) mm2 and a mean cup:disc area ratio of 0.22 (SD 0.13) was observed. Right eyes showed a larger mean retinal nerve fibre layer thickness (RNFLT) (0.263 (SD 0.066) mm) compared with left eyes (0.252 (SD 0.065) mm, p<0.001). Higher values in younger volunteers (mean age 35.7 years) in comparison with elderly participants (mean age 59.1 years) were noted for disc area (1.84 mm2 v 1.78 mm2) and mean RNFLT (0.263 (SD 0.06) mm v 0.249 (SD 0.07) mm) but were not significant (p>0.01). The presented results differ from published data on ONH measurements of healthy volunteers with different techniques. Conclusion: The observed differences in ONH measurements between left and right eyes seem not to be of clinical importance. This is also true for age or sex dependent changes in ONH topographies. The presented data provide a new basis for comparison of optic disc characteristics between healthy eyes and glaucomatous eyes.

Reproducibility of circadian retinal and optic nerve head blood flow measurements by Heidelberg retina flowmetry

Background/aim: The Heidelberg retina flowmeter (HRF) is designed to measure retinal capillary blood flow. Previous studies however showed weak reproducibility of data. The intraindividual reproducibility of circadian HRF measurements was examined in healthy subjects in three locations of the retina. Methods: 36 healthy volunteers (27.3 (SD 4.3) years) were examined by HRF seven times a day (t0–t6). Using a default window of 10×10 pixels, three consecutive measurements were performed in three precise focusing planes: superficial, intermediate and deep layer, peripapillary retina, neuroretinal rim and cup, respectively. Images of identical tissue locations identified by capillary landmarks of each layer were selected to quantify the retinal microcirculation of each volunteer. Means and standard deviations of all flow results of a given subject were calculated, at t0–t6 and the coefficients of variation as a measure of reproducibility. Results: The coefficients of variation ranged between 8.4% and 41.0% in the superficial layer (mean 19.8% (SD 8.4%)), 10.6%, and 43.0% in the intermediate layer (mean 24.0% (SD 8.4%)), and 9.9% and 84.0% (mean 29.6% (SD 15.8%)) in the deep layer. Conclusions: These data show the best reproducibility of measurements in the superficial layer followed by the intermediate and the deep layer. Clinically, this is an unsatisfactory intraindividual reproducibility of flow values in each studied layer.

Association of the optic disc structure with the use of antihypertensive medications: the thessaloniki eye study.

Purpose:To investigate the association of antihypertensive medications with optic disc structure by blood pressure (BP) level, in nonglaucoma subjects. Design:Cross-sectional, population-based study. Methods:A subset of Thessaloniki Eye Study participants was included in this study. Subjects were interviewed for medical history and underwent extensive ophthalmic examination, BP measurement, and optic disc imaging with the Heidelberg retinal tomograph. Subjects treated for hypertension were grouped in the following groups: (1) angiotensin-converting enzyme inhibitors and/or angiotensin-receptor blockers; (2) beta blockers and/or calcium-channel blockers; (3) diuretics alone or combined with others; and (4) other combinations. Cup size and cup-to-disc (C/D) ratio in the above groups were compared with the untreated group, using regression models. Analyses were rerun for subjects with systolic BP (SBP)<140 mm Hg, SBP≥140 mm Hg, diastolic BP (DBP)<90 mm Hg, and DBP≥90 mm Hg. Results:Among 232 subjects, 131 were receiving antihypertensive medications. In subjects with DBP<90 mm Hg, all medications groups were associated with larger cup size and higher C/D ratio compared with the untreated group. Results were similar in subjects with SBP<140 mm Hg, with the exception of the beta blockers and/or calcium-channel blockers group. None of the medications groups were associated with the Heidelberg retinal tomograph parameters in those with DBP≥90 mm Hg or SBP≥140 mm Hg. Conclusions:All classes of antihypertensive medications were associated with larger cup size and higher C/D ratio in subjects with either DBP<90 mm Hg or SBP<140 mm Hg. These results suggest that there is no specific medication-related effect on optic disc structure, and the associations found are mediated through the hypotensive effect of antihypertensive medications.

Long-term fluctuations of the normalised rim/disc area ratio quotient in normal eyes

Abstract · Background. The assessment of the cup of the optic disc in follow-up of glaucomatous optic nerve heads depends on the variability of the cup area over time. We examined the variability of topographic measurements depending on scan focus settings and evaluated the long-term fluctuations of the normalised rim/disc area ratio quotient of normal subjects for 1 year. · Methods. Part 1. Evaluation of the influence of scan focus and corneal curvature on the number of pixels per millimetre in one emmetropic volunteer. The scan focus was varied using contact lenses of different refraction. Part 2. HRT examinations of the optic nerve head of five eyes of five volunteers were repeatedly recorded during a 12-month period. The contour line from the first mean topographic image was transferred into the following seven mean topographic images of each subject. · Results. Part 1. The size of pixels depends on the adjusted scan focus for mean corneal curvature radius between 6 and 9 mm. However, after image to image scaling the size of pixels is nearly independent to the scan focus. Part 2. We found the highest variation of normalised rim/disc area ratio for the location of the temporal horizontal sectors, followed by the temporal inferior and the temporal superior sectors. Variation was smallest in the nasal sectors. Mean fluctuation of the normalised rim/disc area ratio quotient of the 95th percentile was 0.09 following image to image scaling compared to 0.16 when using individual image scaling. · Conclusion. Scan focus variation during HRT follow-up examinations can influence optic disc parameters, especially when image to image scaling has not been performed. A confidence area of an individual optic disc could now be calculated. These confidence bands could help to distinguish more easily between progress of glaucomatous optic nerve head damage and physiological intertopographic variation of optic cup measurements. A decrease of more than 43% in the fluctuations of the normalised rim/disc area ratio could be achieved using image to image scaling techniques. For that reason follow-up of glaucomatous optic nerve heads should only be performed using this software application.

Femtosecond Laser-Assisted Retinal Imaging and Ablation: Experimental Pilot Study

Purpose: To investigate retinal imaging and ablation using femtosecond laser pulses. Materials and Methods: Two non-amplified near-infrared femtosecond lasers were used to irradiate porcine retinal specimens in vitro. The lasers were used for tissue removal as well as multiphoton laser scanning microscopy. Results: Ablation of the nerve fiber layer was performed at pulse energies of 1.0 nJ to 3.9 nJ. Control laser scanning images were acquired within seconds after irradiation. Specimens were additionally investigated with electron microscopy. Conclusions: Non-amplified femtosecond lasers may allow precise surgery controlled by fast high-resolution imaging of the target.

The normalised rim/disc area ratio line

The assessment of the cup of the optic disc depends, among other criteria, on the disc area. A small cup in a small optic disc can indicate an advanced glaucomatous lesion, on the other hand a large cup in a large optic disc can be normal. Therefore, an individual normalised rim/disc area ratio line together with the curves of 50th percentile and the 95th percentile of normal could help to better distinguish between glaucomatous and normal optic cups. The aim of our study was to calculate and to evaluate such a normalised rim/disc area ratio line. Heidelberg Retina Tomograph examinations of the optic nerve head of 100 randomly selected eyes of 100 normal subjects were evaluated. We calculated the disc area adjusted rim/disc area ratio in sectors of 10 degree. The 95th percentile and the 50th percentile of each of the 36 sectors were calculated. Based on these normal percentile lines it was possible to display an individual normalised rim/disc area ratio line in the topographic images of an individual optic disc examination. Here we demonstrated examples of a normal optic disc, optic nerve heads with moderate and advanced lesions and a small optic disc with glaucomatous damage. We present a new display mode of the results of Heidelberg Retina Tomograph optic nerve head examination, which may be helpful for an easy and reliable assessment of glaucomatous optic nerve head damage only looking at topographic images.