Robert Stegmann

Viscocanalostomy for open-angle glaucoma in black African patients

PURPOSE To study the clinical effectiveness of viscocanalostomy in a population of black African patients with open-angle glaucoma that was uncontrolled on medical treatment. SETTING Department of Ophthalmology, Medical University of Southern Africa, Medunsa, South Africa. METHODS In this prospective study viscocanalostomy was performed in 214 eyes of 157 black African patients with open-angle glaucoma that was poorly controlled by medical therapy. The procedure involves the production of superficial and deep scleral flaps. The deep flap is disserted to the plane of Schlemms canal. From this plane, an intact window in Descemets membrane is created by gentle pressure at the level of Schwalbes line using a cellulose sponge. Aqueous humor diffuses through this window into a subscleral space (lake). Reflection of the inner flap unroofs Schlemms canal, creating a trough leading to 2 entrances into Schlemms canal (surgical ostia). A delicate cannula is introduced into the entrance of Schlemms canal left and right and high-viscosity sodium hyaluronate is gently injected into the canal for 4 to 6 mm. The deeper scleral flap is excised (deep sclerectomy) and the superficial flap is sutured securely using 5, 11-0 polyester fiber (Mersilene) sutures. High-viscosity sodium hyaluronate is then injected into the subscleral lake to act as a physical barrier to fibrinogen migration postoperatively. RESULTS Postoperative intraocular pressure (IOP) of 22 mm Hg or less was achieved without medical therapy in 82.7% of eyes. If a beta blocker was added to the cases not achieving 22 mm Hg or less postoperatively, the success rate increased to 89.0%. The average follow-up was 35 months (range 6 to 64 months). CONCLUSION Viscocanalostomy produced an encouraging long-term reduction in the IOP of black African patients with glaucoma who would otherwise have had a poor prognosis.

Canaloplasty for primary open-angle glaucoma: long-term outcome

Background/Aims To study the safety and effectiveness of 360° viscodilation and tensioning of Schlemm canal (canaloplasty) in black African patients with primary open-angle glaucoma (POAG). Methods Sixty randomly selected eyes of 60 consecutive patients with POAG were included in this prospective study. Canaloplasty comprised 360° catheterisation of Schlemms canal by means of a flexible microcatheter with distension of the canal by a tensioning 10-0 polypropylene suture. Results The mean preoperative intraocular pressure pressure (IOP) was 45.0±12.1 mm Hg. The mean follow-up time was 30.6±8.4 months. The mean IOP at 12 months was 15.4±5.2 mm Hg (n=54), at 24 months 16.3±4.2 mm Hg (n=51) and at 36 months 13.3±1.7 mm Hg (n=49). For IOP ≤21 mm Hg, complete success rate was 77.5% and qualified success rate was 81.6% at 36 months. Cox regression analysis showed that preoperative IOP (HR=1.003, 95% CI=0.927 to 1.085; p=0.94), age (HR=1.000, CI=0.938 to 1.067; p=0.98) and sex (HR=3.005, CI=0.329 to 27.448; p=0.33) were all not significant predictors of IOP reduction to ≤21 mm Hg. Complication rate was low (Descemets detachment n=2, elevated IOP n=1, false passage of the catheter n=2). Conclusion Canaloplasty produced a sustained long-term reduction of IOP in black Africans with POAG independent of preoperative IOP. As a bleb-independent procedure, canaloplasty may be a true alternative to classic filtering surgery, in particular in patients with enhanced wound healing and scar formation.

Clinical Evaluation of the Aqueous Outflow System in Primary Open-Angle Glaucoma for Canaloplasty

PURPOSE To assess the aqueous outflow pathway in primary open-angle glaucoma (POAG) through provocative gonioscopy and channelography with a flexible microcatheter and fluorescein tracer during canaloplasty. METHODS One eye each was randomly selected from 28 consecutive black African POAG patients undergoing canaloplasty. Provocative gonioscopy was performed at the beginning of surgery, and blood reflux from collector channels into Schlemms canal (SC) was semiquantitatively evaluated. During canaloplasty, a flexible microcatheter injected fluorescein tracer stepwise into SC. The outflow pathway parameters of interest were blood reflux, transtrabecular passage of fluorescein, and episcleral vein filling. RESULTS Mean age, intraocular pressure (IOP), and cup-to-disc ratio were 45.9 years (SD +/- 13.3), 41.0 mm Hg (SD +/- 11.9), and 0.78 (SD +/- 0.22), respectively. Mean IOP (P < 0.001) and episcleral venous egress (P = 0.01) correlated significantly with blood reflux, but cup-to-disc ratio (P = 0.71), age (P = 0.70), and fluorescein diffusion (P = 0.90) did not. A multinomial regression model showed that higher IOP (P < 0.001, OR, 1.687; 95% CI, 1.151-2.472) was strongly associated with poor blood reflux, independent of the patients age (P = 0.383, OR, 0.942; 95% CI, 0.823-1.078). No correlation was found between preoperative IOP, transtrabecular passage, episcleral venous egress, and cup-to-disc ratio. The mean IOP was 17.5 mm Hg (SD +/- 3.7) 6 months after surgery. The level of IOP after surgery correlated with the grade of blood reflux and episcleral venous egress (P < 0.001). CONCLUSIONS High mean IOP may be associated with poor blood reflux and filling of SC. A collapsed canal, probably secondary to high IOP, may be an underestimated sign in black African patients with POAG. The quality of blood reflux and episcleral venous egress may both be predictive of the level of IOP after surgery. Provocative gonioscopy and channelography may reflect the function of the outflow pathway and may be helpful in assessing the surgical outcome of canaloplasty.

Comparing two tensioning suture sizes for 360° viscocanalostomy (canaloplasty): a randomised controlled trial

PurposeTo compare the safety and efficacy of two polypropylene (Prolene) sutures for tensioning of the inner wall of Schlemms canal (SC) in black African patients with primary open-angle glaucoma (POAG) undergoing canaloplasty.MethodsIn a prospective randomised trial of 90 patients, canaloplasty was performed with a flexible microcatheter (iTrack-250A) and sodium hyaluronidate 1.4% (Healon GV). After complete circumferential dilatation of the SC, a Prolene suture, either 6–0 Prolene (group 1) or 10–0 Prolene (group 2), was retracted through the SC and tightened leaving tension on the canal and trabecular meshwork. Nd:YAG laser goniopuncture was not performed postoperatively.ResultsThe mean preoperative intraocular pressure (IOP) was 42.7 mm Hg±12.5 (SD) in group 1 and 45.0 mm Hg±12.1 (SD) in group 2 (P=0.70). The mean postoperative IOP without medications was 18.4 mm Hg±7.1 (SD) in group 1 and 16.4 mm Hg±6.6 (SD) in group 2 at 1 month (P=0.10), 19.2 mm Hg±6.4 (SD) in group 1 and 16.4 mm Hg±4.9 (SD) at 15 months (P=0.04). Pressures equal or less than 21, 18, and 16 mm Hg without medications (complete success) at 12 months were 51.0% (95% confidence interval (CI) 0.35–0.73), 34.1% (95% CI 0.21–0.56), and 21.2% (95% CI 0.11–0.42) in group 1, and 76.9% (95% CI 0.62–0.96), 68.8% (95% CI 0.54–0.89), and 53.6% (95% CI 0.38–0.76) in group 2, respectively. In the Cox regression analysis, IOP <18 mm Hg without medications depended significantly on the type of Prolene (hazard ratio (HR) 2.60, 95% CI 1.24–5.46, P=0.01) and age (HR 1.3, 95% CI 1.03–1.86, P=0.03), but not on preoperative IOP (HR 1.01, 95% CI 0.99–1.04, P=0.16) and gender (HR 0.67, 95% CI 0.34–1.33, P=0.26). No filtering bleb was observed. Intra- and postoperative complications were similarly rare in the two groups and included partial ‘cheese-wiring’ (2), Descemets rupture (2), and hyphaema (3).ConclusionsIn this clinical trial, IOP reduction was substantial in canaloplasty and slightly greater in combination with 10–0 Prolene than 6–0 Prolene sutures at an equally low complication rate. Younger age, but not the level of IOP at surgery, had a positive effect on the amount of IOP reduction, thus suggesting that an early surgical intervention to re-establish physiological outflow offers the best prognosis.

Posterior vertical capsulotomy with optic entrapment of the intraocular lens in congenital cataracts- : prevention of capsule opacification

Purpose: To present a modified surgical technique for preventing posterior capsule opacification (PCO) in children with congenital cataracts and to evaluate its long‐term efficacy. Setting: Department of Ophthalmology, Medical University of Southern Africa, Medunsa, South Africa. Methods: Anterior and posterior vertical capsulotomy, with optic entrapment of the intraocular lens (IOL) by maintaining the anterior hyaloid, was performed in 68 cataractous eyes of children aged 2 months to 8 years (mean 3 years, 1 month). The posterior capsule was evaluated for at least 5 years for secondary opacification, IOL position, pigmentary deposits on the IOL optic, and the presence of synechias. Results: Sixty‐eight eyes maintained a clear visual axis for 5 to 12 years (mean 9 years, 1 month) postoperatively. No secondary procedure was necessary. In all eyes, the IOL remained well centered and entrapped. Conclusions: Posterior capsulotomy with optic entrapment of the IOL proved to be a safe and efficient surgical procedure for preventing PCO in children with congenital cataracts. Uniting the anterior and posterior capsule in front of the IOL limits the proliferation and migration of Elschnig pearls. An intact anterior hyaloid does not induce capsule opacification in association with optic entrapment; therefore, a vitrectomy is not indicated even in infants under age 5 years. Clear visual axis, centered IOL, and intact vitreous were achieved in this series; this enables a promising long‐term prognosis for binocular visual development, especially because surgery was performed early.

Long-term results of up to 12 years of over 700 cases of viscocanalostomy for open-angle glaucoma.

To study the safety and long‐term efficacy of classic viscocanalostomy in patients with open‐angle glaucoma (OAG) in different populations.

Novel device for expanding Schlemm's canal: a morphological study: Implantation of the Stegmann Canal Expander following viscodilation of Schlemm's canal resulted in permanent expansion of the canal lumen and distension of the trabecular meshwork without complications

This study was performed to assess any changes in Schlemms canal (SC) in human autopsy eyes possibly resulting from the injection of a viscoelastic substance and implantation of a new device (the Stegmann Canal Expander, SCE) into SC. After the surgical procedure, eyes were fixed, dissected into quartered segments and examined using light and scanning electron microscopy. Tissue sections displayed a marked dilation of SC and of the collector channels compared with untreated control sections. The SC walls were disrupted in some areas due to viscodilation, but not due to SCE implantation. In all eyes, the entire 9-mm length of the SCE was positioned inside the canal, keeping the canal wide open. The SCE diameter of 240 μm remained unchanged after implantation. Injection of a viscoelastic substance into SC leads to marked dilation of SC and collector channels. Implanting the SCE into SC allowed persistent expansion of SC and stretching of the trabecular meshwork. This may increase the permeability of the trabecular meshwork, reduce its resistance to aqueous humour and maintain circumferential flow within SC. Experimental and clinical studies should determine the impact of this new canal expander in terms of lowering intraocular pressure in glaucoma surgery.

Novel device for expanding Schlemm9s canal: a morphological study

This study was performed to assess any changes in Schlemms canal (SC) in human autopsy eyes possibly resulting from the injection of a viscoelastic substance and implantation of a new device (the Stegmann Canal Expander, SCE) into SC. After the surgical procedure, eyes were fixed, dissected into quartered segments and examined using light and scanning electron microscopy. Tissue sections displayed a marked dilation of SC and of the collector channels compared with untreated control sections. The SC walls were disrupted in some areas due to viscodilation, but not due to SCE implantation. In all eyes, the entire 9-mm length of the SCE was positioned inside the canal, keeping the canal wide open. The SCE diameter of 240 μm remained unchanged after implantation. Injection of a viscoelastic substance into SC leads to marked dilation of SC and collector channels. Implanting the SCE into SC allowed persistent expansion of SC and stretching of the trabecular meshwork. This may increase the permeability of the trabecular meshwork, reduce its resistance to aqueous humour and maintain circumferential flow within SC. Experimental and clinical studies should determine the impact of this new canal expander in terms of lowering intraocular pressure in glaucoma surgery.

The role of the limbal cornea in vision

The eagle retina is bifoveal. The temporal fovea, which can resolve targets subtending half a minute or less must depend upon its peripheral cornea for such sharp resolution. Our studies showed the eagle cornea to be thinner, scatter less light and be more spherical than the human cornea. Further experimental studies determined the resolving power of the human peripheral cornea. Using, normal subjects, pinholes placed at the edge 8 mm dilated pupils yielded 20/30 visual acuity and normal contrast sensitivity measurements. Thus it is recommended that optical iridectomy be considered, in appropriate cases of corneal blindness with patches of clear peripheral cornea when no donor corneal material is available.

A New Expander for Schlemm Canal Surgery in Primary Open-angle Glaucoma-Interim Clinical Results.

Purpose:To evaluate a new canal expander in circumferential viscocanalostomy (canaloplasty) for whites with primary open-angle glaucoma (POAG). Design:Prospective, single-center, noncomparative study. Participants:Twenty-two eyes of 22 consecutive patients with medically uncontrolled POAG underwent primary viscocanalostomy and implantation of the Stegmann Canal Expander into Schlemm canal with a follow-up time of at least 1 year. Materials and Methods:Schlemm canal was unroofed ab externo, and dilated with viscoelastic material and microcatheter. The Stegmann Canal Expander is a flexible, fenestrated hollow implant of 9 mm in length. One expander was implanted into either side of the surgically created of ostium to keep the Schlemm canal permanently open. The superficial scleral flap was closed watertight. Laser goniopuncture of the trabeculo-Descemet membrane window was performed if postoperative intraocular pressure (IOP) exceeded 16 mm Hg. Main Outcome Measures:Complete successes were defined as a confirmed IOP⩽21, ⩽18, and ⩽16 mm Hg without medications, respectively, combined with a 30% IOP reduction. Number of antiglaucomatous medications, best-corrected visual acuity, and intraoperative and postoperative complications were recorded. Results:The mean IOP dropped from 27.1±5.3 mm Hg preoperatively to 13.6±1.6 mm Hg at 6 months, 13.0±1.5 mm Hg at 9 months, and 13.1±2.2 mm Hg at 12 months (P<0.001). The complete success rates for an IOP⩽21, ⩽18, and ⩽16 mm Hg combined with a 30% IOP reduction were 91% [95% confidence interval (CI), 0.80-1.0], 91% (95% CI, 0.80-1.0), and 91.0% (95% CI, 0.80-1.0) at 6 months, and 86% (95% CI, 0.73-1.0), 82% (95% CI, 0.67-1.0), and 82.0% (95% CI, 0.67-1.0) at 12 months. The success rate of an IOP⩽16 mm Hg without medications did not depend on age [hazard ratios (HR) 1.02; 95% CI, 0.85-1.12; P=0.74], preoperative IOP (HR 0.97; 95% CI, 0.83-1.23; P=0.89), and mean visual defect (HR 1.05; 95% CI, 0.72-1.27; P=0.76). Laser goniopuncture was performed on 2 eyes (9%) 4.1 months postoperatively; the mean IOP was 19.5 mm Hg before and 13.6 mm Hg after goniopuncture. The number of medications dropped from 2.9±0.6 before surgery to 0.05±0.2 after surgery (P<0.001). The postoperative best-corrected visual acuity at last visit (0.12±0.09; range, 0 to 0.39) was comparable to preoperative values (mean±SD, 0.16±0.10; range, 0 to 0.39) (P=0.35). Minor intraoperative or postoperative complications included microhyphema (8 eyes) and transient elevated IOP (steroid responder; 2 eyes). Conclusions:Implantation of the Stegmann Canal Expander in canaloplasty lowered IOP significantly in POAG without complications related to the device in this 1-year observation period.