A. M. Peter Hamilton

Phacoemulsification versus extracapsular cataract extraction in patients with diabetes

OBJECTIVE To compare phacoemulsification with extracapsular cataract surgery in patients with diabetes and to identify determinants of postoperative visual acuity. DESIGN Prospective, randomized, paired-eye trial. PARTICIPANTS Forty-six patients with diabetes and bilateral cataract. INTERVENTION Patients were allocated to phacoemulsification surgery with silicone intraocular lens to one randomly determined eye, and extracapsular cataract surgery with 7-mm polymethylmethacrylate intraocular lens to the other. MAIN OUTCOME MEASURES Logarithm of minimum angle of resolution visual acuity (logMAR VA), incidence of clinically significant macular edema (CSME), retinopathy progression, indices of anterior segment inflammation, and incidence of capsulotomy. RESULTS Compared with eyes undergoing phacoemulsification, eyes managed with extracapsular surgery had more anterior chamber cells (P = 0.0004) and flare (P = 0.007) 1 week after surgery and a higher incidence of posterior synechiae (P = 0.04) and intraocular lens deposits (P < 0.0005) in the first postoperative year. The need for posterior capsulotomy was greater in eyes undergoing extracapsular surgery (16 of 46 vs. 5 of 46, P = 0.01). No difference in incidence of postoperative CSME, progression of retinopathy, or development of high-risk proliferative retinopathy was identified between techniques (P = 1.0, 0.8, and 0.2). Median 1-year logMAR VA was worse in eyes undergoing extracapsular surgery (0.08 vs. 0.06, P = 0.02), especially in those with retinopathy (0.14 vs. 0.08, respectively; P = 0.01). The presence or absence of CSME at the time of surgery was the most significant determinant of 1-year logMAR VA in regression models for both extracapsular (P = 0.0004, R2 = 0.45) and phacoemulsification groups (P < 0.00005, R2 = 0.46). CONCLUSIONS Phacoemulsification is associated with better postoperative VA, less postoperative inflammation, and less need for capsulotomy than extracapsular cataract surgery in patients with diabetes. However, with both techniques, the principal determinant of postoperative VA appears to be the presence or absence of CSME at the time of surgery. Early intervention, reducing the risk that unrecognized CSME is present at the time of surgery, may be more critical to outcome than choice of surgical technique.

Extracapsular Cataract Surgery with and without Intraocular Lens Implantation in Fuchs Heterochromic Cyclitis

PURPOSE To compare the surgical and postoperative complications and visual outcome of extracapsular cataract extraction (ECCE) with and without intraocular lens (IOL) implant in Fuchs heterochromic cyclitis. METHODS The records of 77 patients with Fuchs heterochromic cyclitis who had undergone ECCE were reviewed. Of a total of 77 eyes, a posterior chamber IOL (PC IOL) was implanted in 43 eyes, whereas 34 eyes did not receive an implant. RESULTS In the pseudophakic group, 40 (93%) eyes achieved 20/40 or better. This level also was achieved in 29 (85%) eyes not receiving an implant. Intraoperative anterior chamber hemorrhage was documented in 18 eyes but there was no correlation with preoperative gonioscopic findings. A temporary or permanent elevation of intraocular pressure was noted in five of eight eyes that had marked anterior chamber hemorrhage. Severe postoperative uveitis occurred in ten eyes and was more common in patients with glaucoma who had PC IOL implantation, but this did not adversely affect the visual outcome. Of 40 eyes with PC IOL implant, severe postoperative uveitis developed in 7. In six of these seven eyes, the implant was a three-piece lens with polypropylene haptics. Severe postoperative uveitis developed in 6 of 16 eyes with preoperative glaucoma. Five of these six eyes had a PC IOL implant. Of the 34 aphakic patients, 10 (29%) were intolerant of contact lens correction. There was no difference in the incidence of postoperative uveitis, cystoid macular edema, and development of glaucoma between the two groups. CONCLUSION Implantation of PC IOLs in ECCE in patients with Fuchs heterochromic cyclitis appears to a safe procedure, but careful postoperative follow-up of intraocular pressure, particularly in patients with intraoperative hemorrhage or postoperative uveitis, is indicated.

Color Contrast Sensitivity and Pattern Electroretinographic Findings After Diode and Argon Laser Photocoagulation in Diabetic Retinopathy

The retinal depth at which photocoagulation is maximal varies with wavelength. We compared visual function of eyes undergoing photocoagulation by the near-infrared diode laser to the argon green laser. We treated 14 patients with diabetic retinopathy requiring bilateral panretinal photocoagulation with the diode laser on the right eye and the argon system on the left eye. Before and after treatment visual acuity, central and peripheral color contrast sensitivity, and pattern electroretinograms were recorded. No difference was noted in the clinical response or visual acuity outcome, but a tendency was observed for less decline in color contrast sensitivity and pattern electroretinogram recordings after diode laser photocoagulation. Although P values (.05 to .5) did not reach significance, a mean of 8.4 of 14 patients per test had better test results after diode laser treatment. Diode laser photocoagulation seems to be a viable alternative to argon laser treatment and may be a more gentle mode of treatment.

Long-term Follow-up of Diode Laser Trabeculoplasty for Primary Open-angle Glaucoma and Ocular Hypertension

BACKGROUND Initial studies of laser trabeculoplasty using infrared energy (810 nm) emitted by diode semi-conductor lasers have been encouraging. A 2-year study of diode laser trabeculoplasty (DLT) in the control of primary open-angle glaucoma (POAG) and ocular hypertension has been completed. METHODS Patients with uncontrolled POAG or ocular hypertension were treated with DLT to one half of the trabecular meshwork using a trabeculoplasty lens. Spot size was 100 microns, exposure time was 0.2 second, and mean power was 1096 mW (+/- 46.5 mW). The desired endpoint was a mild blanching of the meshwork only. RESULTS Twenty-five eyes of 16 patients were treated. Mean intraocular pressure reduction was 9.24 mmHg (+/- 3.4 mmHg) at 6 weeks, 9.32 mmHg (+/- 3.6 mmHg) at 3 months, 9.34 mmHg (+/- 3.8 mmHg) at 6 months, 8.42 mmHg (+/- 2.62 mmHg) at 12 months, 8.14 mmHg (+/- 3.42 mmHg) at 18 months, and 7.9 mmHg (+/- 3.63 mmHg) at 24 months. No pressure peaks (> 5 mmHg) were recorded after therapy. Inflammation and discomfort were minimal after laser treatment. Of 16 eyes examined at 2 years, there were no peripheral anterior synechiae. During the course of the study, six eyes became uncontrolled, despite one session of DLT. Four eyes regained control with a further session of DLT, but two required trabeculectomy. CONCLUSION Diode laser trabeculoplasty is an effective form of therapy in POAG and ocular hypertension. Hypotensive effects and success rates are comparable with argon laser trabeculoplasty (ALT). Reduced inflammation after laser treatment may be due to reduced absorption of infrared energy by the melanin of the anterior segment. The portable nature of these lasers may allow for laser delivery in developing countries and remote situations.

Q-switched neodymium YAG laser vitreolysis in the therapy of posterior segment disease

We describe our experience of ten cases of posterior segment vitreolysis, using the short-pulse neodymium YAG (Yittrium Aluminium Garnate) laser. Eight patients had proliferative diabetic retinopathy, one patient had had an intraocular foreign body removed and one patient had had uveitis. Of the ten, five patients had macular traction retinal detachments, three patients had progressive traction retinal detachments threatening the macula and two patients had recurrent vitreous haemorrhages from mechanical traction on areas of fibrovascular proliferation. Eight of the patients were successfully treated. One macular retinal detachment failed to flatten and a tear was found which may have been iatrogenic. In one patient with a traction retinal detachment significant traction was relieved but the detachment failed to flatten completely. We discuss the indications, techniques, difficulties and complications. Our experience suggests that this technique has an important role in the treatment of selected patients, sparing patients conventional vitrectomy, or making possible the treatment of those for whom vitrectomy has been contraindicated or refused. Anterior defocussing of the YAG would be a useful modification of current laser systems and improved aiming systems desirable for the future.

Partial Laser Ablation of Massive Peripapillary Subretinal Neovascularization

BACKGROUND Although peripapillary subretinal neovascular membranes (PSRNs) are less common and often larger than neovascular complexes arising near the fovea, they may lead to severe visual loss. Very large (massive) PSRNs (MPSRNs) are 3.5 disc areas or greater in overall size, are even less common, and may contain a significant occult component, leading to slow and unpredictable growth. Such massive lesions may begin at the nasal margin of the disc and do not become symptomatic until they have extended around the disc toward the macula, threatening central vision. Although complete laser ablation has been used for symptomatic PSRNs with variable success, the optimal treatment of MPSRNs remains controversial. METHODS The authors reviewed the clinical course of 12 eyes of seven patients with MPSRNs. Ten eyes received laser treatment, which was limited to the temporal portion of the subretinal neovascular complexes only and two received no treatment. RESULTS Of the ten eyes receiving laser treatment, six showed stabilization of visual acuity, whereas in four the neovascular membrane progressed beneath the fovea with severe visual loss. In the two untreated eyes, the subretinal neovascular membrane progressed beneath the macula with the loss of central vision. CONCLUSIONS In contrast to the small symptomatic PSRNs, which are usually treated by complete laser ablation, MPSRNs may stabilize with only partial laser treatment. However, both types of lesions may remain stable for long periods of time without any treatment and require treatment only if progression toward the fovea occurs.

Macular oedema and retinal neovascularisation in juvenile diabetics

Thirteen young diabetic patients with peripheral capillary non perfusion who presented with symptoms of mild maculopathy were reviewed retrospectively. In this group, peripheral retinal ischaemia was often overlooked and a rapidly progressive proliferative retinopathy developed. Fluorescein angiography of the peripheral retina showed capillary closure, but with preservation of arterioles and venules.In this series, half of the eyes lost vision. In seven eyes where the peripheral ischaemia was treated by pan retinal photocoagulation, the maculopathy resolved without any specific laser treatment to the macula.In young diabetics presenting with maculopathy, the peripheral retina should be examined for ischaemia, and if present, pan retinal laser photocoagulation should be performed. Focal treatment for the macular disease can be delayed until after the peripheral photocoagulation, as the maculopathy may remit.

Panretinal photocoagulation during cataract extraction in eyes with active proliferative diabetic eye disease

Purpose Cataract surgery in the presence of active proliferative diabetic eye disease carries a high risk of progression of retinopathy and neovascular glaucoma. Lens opacities may prevent panretinal photocoagulation (PRP) before surgery, and applying PRP in the immediate post-operative period can be difficult. The purpose of this study is to report results of cataract extraction combined with per-operative indirect laser PRP in a group of these patients.Methods Nine eyes of 9 diabetic patients with active retinal or iris neovascularisation in which lens opacities prevented adequate pre-operative PRP underwent cataract surgery combined with indirect laser PRP after cortex aspiration and before intraocular lens implantation.Results Regression of neovascularisation with this combined procedure alone was achieved in 5 eyes, 3 responded to further PRP, and 1 developed neovascular glaucoma. Visual acuity improved in all eyes, 4 achieving ≥6/12. Four patients developed increased postoperative uveitis. One developed clinically significant macular oedema.Conclusions The method described has definite practical advantages over PRP attempted in the immediate post-operative period, when many factors can prevent its application or reduce its effectiveness, and when neovascularisation may be progressing rapidly. In addition, adjunctive per-operative indirect laser PRP appears to improve the outcome of cataract surgery in eyes with active proliferative diabetic eye disease.