Medical Library

Cost-effectiveness of reducing wait times for cataract surgery in Ontario.

Background: Reducing wait times for cataract surgery is a priority in Ontario. However, no previous analysis has determined whether the extra treatment volumes required to reduce wait times are of good monetary value when compared with allocating those same financial resources to new programs, drugs, or technologies. The objective of the study was to use queuing models to determine the cost-effectiveness of reducing, to target levels, wait times for cataract surgery at the provincial level within 1 to 10 years by increasing treatment volumes.Methods: A cost-effectiveness analysis was performed by estimating the extra treatment volume required to reduce wait times using queuing model methodology. The cost of these extra treatments was obtained from Ontario provincial data. The incremental benefits of surgery are improvements in quality-adjusted life years (QALYs), and these values were obtained from the clinical literature. Incremental costs were compared with incremental benefits to determine an incremental cost-effectiveness ratio.Results: To reach the publicly stated target wait times, annual treatment volumes must increase by 4%. An extra increase in treatment volumes of 25,660 must also be provided for the transition period from the current wait time. The incremental cost-effectiveness ratio is $17,829 per QALY if the target wait time is achieved in 5 years, and this ratio is less than the common threshold for approval of new interventions, of $50,000 per QALY.Interpretation: Increasing treatment volumes is a cost-effective way of reducing wait times.

Hopkins RB, Tarride JE, Bowen J, Blackhouse G, O\’Reilly D, Campbell K, Lim M, Goeree R.

Variants of RP1 gene in Chinese patients with autosomal dominant retinitis pigmentosa.

Background: The objective of this study was to determine the frequency and characteristics of mutations in the RP1 gene and to characterize mutations with the clinical features in the Chinese family with autosomal dominant retinitis pigmentosa (ADRP).Methods: Forty-three affected, unrelated Chinese individuals with ADRP were recruited between 2002 and 2006. Polymerase chain reaction and direct DNA sequencing were used to screen in the entire coding region and splice sites of the RP1 gene. Cosegregation analysis and population frequency studies were performed for patients with identified mutations. The clinical features were determined by complete ophthalmologic examinations.Results: The mutation detectable rate of the RP1 gene in Chinese patients with ADRP was 1/43. A missense mutation, N985Y, was identified in exon 4 of the RP1 gene in 8 affected individuals from a Chinese family with ADRP. The ophthalmic findings with an N985Y mutation were similar to those of typical retinitis pigmentosa with delayed onset after age 40 years and slow progression. In addition, a total of 9 distinct variants were detected in our study population, most of which were RP1 gene polymorphisms; the pathological significance of P903L, a novel missense mutation, was unconfirmed.Interpretation: Mutations in the RP1 gene are relatively rare in Chinese patients with ADRP. In our cases, N985Y mutation segregated with the phenotype from 1 Chinese family with mild and late-onset ADRP, a finding that has not been documented in other races.

Sheng X, Zhang X, Wu W, Zhuang W, Meng R, Rong W.

Retina remodeling following diode laser.

Background: The purpose of this study was to characterize the sequential development of focal and surround retinal injury and repair following transscleral diode laser to rat retina.Methods: Transscleral laser photocoagulation of the retina was induced with a diode laser (DioPexy Probe, 810 nm, 200 mW, 2 seconds) in adult Long-Evans rats. The right eye of rats with survival times of 0 days (n = 4), 5 days (n = 6), 2 weeks (n = 4), 6 weeks (n = 6), and 12 weeks (n = 4) was studied. Using serial sections, detailed pathological changes in laser-treated and surrounding retinal and choroidal areas were compared with the control fellow eye.Results: Photocoagulation damage was limited to the retina, sparing Bruch\’s membrane, with minimal choroidal involvement in almost all cases (23/24 eyes). Following damage to the neural retina, the sequence of major remodeling processes was consistent and included inflammatory response, reparative changes, and formation of glial-vascular scar with neovascularization.Interpretation: This new laser model caused reproducible injury, inflammation, and scarring confined to the retina, and may be a tool to help test the effects of candidate neuroprotective/regenerative agents on retinal degeneration to prevent vision loss.

Pozdnyakov S, Gupta N, Yeung J, Yücel Y.

Combined rhegmatogenous and traction retinal detachment in proliferative diabetic retinopathy: clinical manifestations and surgical outcome.

Background: Combined rhegmatogenous and traction retinal detachment (combined detachment) is a serious complication in proliferative diabetic retinopathy. The common clinical findings and surgical results of this complication were investigated.Methods: Forty eyes of 36 consecutive patients with combined detachment undergoing pars plana vitrectomy at a teaching hospital in a 4.5-year period were retrospectively reviewed. All cases had been followed up for at least 6 months.Results: Only 10 of the 40 cases had a preoperative visual acuity better than finger counting vision. Extensive proliferation with multiple, thickened, plaque-like vitreoretinal adhesions and large areas of detachment were noted in 38 cases, 19 cases showing predominantly fibrous tissue and 19 cases presenting with predominantly active fibrovascular proliferation. Two cases had minimal fibrovascular proliferation. Retinal breaks were identified in 7 eyes (17.5%) before surgery and in 33 eyes (82.5%) during surgery. Thirty-seven eyes (92.5%) achieved long-term retinal reattachment. Silicone oil was used in 23 eyes (57.5%). Visual acuity improved in 28 eyes (70%), was unchanged in 6 (15%), and became worse in 6 (15%). In 19 eyes postoperative vision was better than 20/400. Multiple regression analysis showed preoperative visual acuity as the single factor associated with postoperative visual outcome.Interpretation: Combined retinal detachment in proliferative diabetic retinopathy may occur during the stage of active fibrovascular proliferation or as a late complication. It is frequently associated with tightly adherent preretinal tissue and extensive detachment. Preoperative visual acuity best predicts visual prognosis.

Yang CM, Su PY, Yeh PT, Chen MS.

A screening strategy for the detection of sickle cell retinopathy in pediatric patients.

Background: Children with sickle cell hemoglobinopathy are referred routinely to detect retinopathy and thereby prevent vision-threatening complications. This study aimed to determine the prevalence and age of onset of clinically significant retinopathy in such patients, and to recommend a screening strategy for ophthalmologists.Methods: Two hundred sixty-three pediatric sickle cell patients to a maximum age of 18 years during the period of observation were reviewed for the onset of retinopathy, considering the influence of hemoglobin genotype, gender, and the presence of systemic manifestations.Results: Proliferative retinopathy (PR) was rare. Six cases (8.2%) of PR were seen in the SC genotype, 1 case (0.6%) in the SS genotype, and no cases in the SB-Thalassemia genotype. The age of onset of PR was a mean of 13.7 years (median 13, range 9-18) in the SC genotype and 16 years in the SS genotype. Neither gender nor the presence of systemic manifestations was predictive for the prevalence or age of onset of retinopathy.Interpretation: Screening for retinopathy may begin at age 9 years for SC genotype patients and at age 13 years for SS and SB-Thalassemia genotype patients. Serial examinations may be done biennially for eyes with normal findings. Patients with an abnormal examination should undergo fluorescein angiography and be followed as necessary.

Gill HS, Lam WC.

Age-related macular degeneration and low-vision rehabilitation: a systematic review.

Background: Because of the prevalence and devastating consequences of age-related macular degeneration (AMD), a systematic review devoted to low-vision rehabilitation and AMD seems timely and appropriate. Methods: Several electronic databases were searched for studies from 1980 to 2006 involving individuals with low vision or visual impairment and rehabilitation interventions. Studies were assessed for quality and level of evidence.Results: The findings indicate that standard low-vision rehabilitation programs, conventional in-clinic assessments, and optical devices are effective ways of managing and living with vision loss. Areas of unmet need include determining which types of orientation and mobility programs and devices are most effective and developing methods of matching assistive technologies with the individual\’s visual and environmental requirements. Interpretation: Additional randomized controlled trials with similar intervention comparisons and outcome measures are needed to form stronger conclusions for the most effective low-vision rehabilitation interventions for individuals with AMD.

Hooper P, Jutai JW, Strong G, Russell-Minda E.

Blepharitis: current strategies for diagnosis and management.

Background: The aim of this article is to present a consensus on the appropriate identification and management of patients with blepharitis based on expert clinical recommendations for 4 representative case studies and evidence from well-designed clinical trials.Methods: The case study recommendations were developed at a consensus panel meeting of Canadian ophthalmologists and a guest ophthalmologist from the U.K., with additional input from family doctors and an infectious disease/medical microbiologist, which took place in Toronto in June 2006. A MEDLINE search was also conducted of English language articles describing randomized controlled clinical trials that involved patients with blepharitis.Results: Blepharitis involving predominantly the skin and lashes tends to be staphylococcal and (or) seborrheic in nature, whereas involvement of the meibomian glands may be either seborrheic, obstructive, or a combination (mixed). The pathophysiology of blepharitis is a complex interaction of various factors, including abnormal lid-margin secretions, microbial organisms, and abnormalities of the tear film. Blepharitis can present with a range of signs and symptoms, and is associated with various dermatological conditions, namely, seborrheic dermatitis, rosacea, and eczema. The mainstay of treatment is an eyelid hygiene regimen, which needs to be continued long term. Topical antibiotics are used to reduce the bacterial load. Topical corticosteroid preparations may be helpful in patients with marked inflammation.Interpretation: Blepharitis can present with a range of signs and symptoms, and its management can be complicated by a number of factors. Expert clinical recommendations and a review of the evidence on treatment supports the practice of careful lid hygiene, possibly combined with the use of topical antibiotics, with or without topical steroids. Systemic antibiotics may be appropriate in some patients.

Jackson WB.

The Boston Keratoprosthesis in severe ocular trauma.

Background: In eyes with corneal disease and opacity so severe that standard corneal transplantation carries a poor prognosis, a keratoprosthesis (KPro) may still be successful in providing functional visual acuity. The purpose of this study was to determine the outcome of Boston KPro implantation in the rehabilitation of severe ocular trauma.Methods: This is a retrospective study of 30 eyes (30 patients) with severe ocular trauma that underwent Boston KPro type I implantation at the Massachusetts Eye and Ear Infirmary. Of these 30 eyes, 6 had mechanical trauma, 21 had chemical burns, and 3 had thermal burns. The measures used in this review are 5-fold: (i) anatomic success; (ii) number of postoperative repair procedures performed; (iii) preoperative and postoperative visual acuity; (iv) number of eyes with concomitant preoperative retinal or optic nerve damage prior to KPro surgery; and (v) incidence of postoperative complications.Results: Preoperative visual acuity ranged from counting fingers to light perception (median: hand motion). Best-corrected postoperative visual acuity ranged from 20/20 to no light perception (median: 20/80). Anatomic success was achieved in 5 out of 5 mechanically traumatized eyes, 14 out of 17 eyes with chemical burns, and 3 out of 3 eyes with thermal burns. Repair procedures were done in 8 of the 17 chemically burned eyes. The number of eyes with concomitant preoperative ocular disease was 2 out of 6 in the mechanical trauma group, 10 out of 21 in the chemical burn group, and 1 out of 3 in the thermal burn group. The incidence of postoperative complications was greater in the chemical burn group than in either the mechanical trauma or the thermal burn group. Interpretation: The Boston KPro can provide considerable visual improvement and a long-term anatomic retention rate in severely traumatized eyes. The overwhelming danger in severe chemical burns is glaucoma progression despite a functioning tube implant and normal intraocular pressure.

Harissi-Dagher M, Dohlman CH.

Cyclops.

Steinbach MJ.

Circulating uveal melanoma cells: should we test for them? / Devrait-on faire un test de détection des cellules métastatiques circulantes du mélanome de l\’uvée ?

Fernandes BF, Belfort RN, Di Cesare S, Burnier MN Jr.