Effect of hydroxychloroquine or chloroquine and short wavelength light on in vivo retinal function and structure in mouse eyes

CLINICAL RELEVANCE

The use of chloroquine or hydroxychloroquine can lead to both acute and chronic changes to both retinal structure and function.

BACKGROUND

Chloroquine (CQ) and hydroxychloroquine (HCQ) have the potential for retina toxicity. The acute impact of short-term drug exposure (2-4 weeks) on in vivo retinal structure and function and assess whether short wavelength light exposure further exacerbates any structural and functional changes was assessed in a murine model.

METHODS

Adult C57BL/6 J mice received intraperitoneal injection of vehicle or hydroxychloroquine (10 mg/kg) 3 times per week for 2 or 4 weeks, or chloroquine for 4 weeks (10 mg/kg). Over this period, animals were exposed to room light (8 hours) or short-wavelength light 4 hours per day (4 hours of normal room light) for 5 days each week. Retinal changes were assessed using electroretinography (ERG), in vivo optical coherence tomography (OCT) imaging.

RESULTS

Short-term low-dose HCQ and CQ treatment led to RPE thickening and elongation of photoreceptors. These structural changes were associated with a no dysfunction in the case of HCQ treatments and widespread functional changes (photoreceptor sensitivity, bipolar cell amplitude and oscillatory potential amplitude) in the case of CQ treatment. Exposure to low intensity short-wavelength light does not appear to alter the effect of HCQ or CQ.

CONCLUSIONS

HCQ and CQ treatment has acute effects on both retinal structure and function, effects that were not exacerbated by short wavelength light exposure. Whether chronic short wavelength light exposure exacerbates these changes require further study.

Development of a surgical procedure for implantation of a prototype suprachoroidal retinal prosthesis

BACKGROUND

Current surgical techniques for retinal prosthetic implantation require long and complicated surgery, which can increase the risk of complications and adverse outcomes.

METHOD

The suprachoroidal position is known to be an easier location to access surgically, and so this study aimed to develop a surgical procedure for implanting a prototype suprachoroidal retinal prosthesis. The array implantation procedure was developed in 14 enucleated eyes. A full-thickness scleral incision was made parallel to the intermuscular septum and superotemporal to the lateral rectus muscle. A pocket was created in the suprachoroidal space, and the moulded electrode array was inserted. The scleral incision was closed and scleral anchor point sutured. In 9 of the 14 eyes examined, the device insertion was obstructed by the posterior ciliary neurovascular bundle. Subsequently, the position of this neurovascular bundle in 10 eyes was characterized. Implantation and lead routing procedure was then developed in six human cadavers. The array was tunnelled forward from behind the pinna to the orbit. Next, a lateral canthotomy was made. Lead fixation was established by creating an orbitotomy drilled in the frontal process of the zygomatic bone. The lateral rectus muscle was detached, and implantation was carried out. Finally, pinna to lateral canthus measurements were taken on 61 patients in order to determine optimal lead length.

RESULTS

These results identified potential anatomical obstructions and informed the anatomical fitting of the suprachoroidal retinal prosthesis.

CONCLUSION

As a result of this work, a straightforward surgical approach for accurate anatomical suprachoroidal array and lead placement was developed for clinical application.

Intravitreal bevacizumab in inflammatory ocular neovascularization

PURPOSE

To assess the role of bevacizumab in inflammatory ocular neovascularization.

DESIGN

Retrospective, multicenter, consecutive case series of inflammatory ocular neovascularization.

METHODS

Patients with inflammatory ocular neovascularization of varying causes for whom standard therapy failed were treated with intravitreal injection of bevacizumab. Main outcome measures included improvement of best-corrected visual acuity (BCVA) expressed in logarithm of minimum angle of resolution units, response of inflammatory ocular neovascularization by funduscopy and angiography, and decrease in central foveal thickness as measured by optical coherence tomography at the three-month follow-up.

RESULTS

At the three-month follow-up, 84 eyes of 79 patients had been treated with a mean of 1.3 injections (range, one to three). Thirty-four eyes showed juxtafoveal choroidal neovascularization (CNV), 34 eyes showed subfoveal CNV, eight eyes showed peripapillary CNV, and 11 eyes showed neovascularization of the disc (NVD) or neovascularization elsewhere (NVE). BCVA improved 2.4 lines from 0.68 (6/28 or 20/94) to 0.44 (6/17 or 20/55) (P < .001). BCVA improved by one to three lines in 34.5% of the eyes, by four to six lines in 16.7% of the eyes, and by more than six lines in 14.2% of the eyes. Function was unchanged in 23.8% of the eyes. BCVA worsened in 10.7% (zero to three lines in 7.1%, more than four lines in 3.6%). Central foveal thickness decreased from baseline 346 to 252 microm (P < .001). For CNV, 32 eyes (43.2%) had complete regression after the injection, 27 (36.5%) had partial regression, five (6.8%) had no response, and 10 eyes (13.5%) were not evaluated by the contributors. For NVD or NVE, seven eyes (63.6%) had complete regression of new vessels and four eyes (36.4%) had partial regression after the injection.

CONCLUSIONS

Intravitreal bevacizumab led to short-term significant visual improvement and regression of inflammatory ocular neovascularization in a wide variety of inflammatory ocular diseases.

Age related macular degeneration

INTRODUCTION

Sight-threatening (late) age-related macular degeneration (AMD) occurs in 2% of people aged over 50 years in industrialised countries, with prevalence increasing with age. Early-stage disease is marked by normal vision, but retinal changes (drusen and pigment changes). Disease progression leads to worsening central vision, but peripheral vision is preserved.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of interventions to prevent progression of early- or late-stage age-related macular degeneration; and exudative age-related macular degeneration? We searched: Medline, Embase, The Cochrane Library and other important databases up to March 2006 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 45 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: antiangiogenesis (using pegaptanib, ranibizumab, interferon alfa-2a, or anecortave acetate), antioxidant vitamins plus zinc, external beam radiation, laser treatment to drusen, photodynamic therapy with verteporfin, submacular surgery, thermal laser photocoagulation, transpupillary thermotherapy.

Pain and vomiting after vitreoretinal surgery: a potential role for local anaesthesia

Periconal local anaesthesia with subtenon supplementation was used to provide anaesthesia for 94 patients having vitreoretinal surgery. Of these, 44 patients also received general anaesthesia with neuromuscular block. None of these patients received opioid or antiemetic before or during surgery. In comparison with a retrospective control group, patients who had received local anaesthesia as part of their anaesthetic technique were less likely to be given a parenteral opioid (P < 0.001) or to vomit (P < 0.001) within six hours of the completion of surgery. They also experienced significantly fewer bradycardic episodes during surgery (P = 0.001). For patients having general anaesthesia, administration of an intraoperative antiemetic reduced the incidence of vomiting within six hours of the completion of surgery (P = 0.008). For patients who did not receive local anaesthetic, shorter operating time was a factor associated with both reduced postoperative vomiting (P = 0.0015) and administration of parenteral opioid (P = 0.0014). It is suggested that the use of local anaesthesia as part of the anaesthetic technique for vitreoretinal surgery is associated with improved patient comfort.

Macular holes. Pathogenesis, natural history and surgical outcomes

Idiopathic full-thickness macular holes (FTMH) are a common cause of usually uniocular reduced visual acuity. The accepted pathogenesis has macular hole formation proceeding in stages from an impending hole to a FTMH, with visual acuity deteriorating to less than 6/60 in 85% of cases. Recent surgical advances in the treatment of FTMH, with excellent anatomic and visual results, have changed the surgical indications for both impending and established full-thickness macular holes.

Penetrating ocular injury following local anaesthesia

A series of 13 cases of globe perforation following local ocular anaesthesia are reported. All cases were associated with cataract surgery. Perforation occurred with the retrobulbar approach in nine cases and with the peribulbar approach in two cases. In two cases the approach for local anaesthesia was not recorded. In 12 of the 13 cases, a perforating wound was found in the inferotemporal quadrant. All cases were found to have vitreous haemorrhage. All cases had significant posterior segment injury. Vitrectomy was carried out in nine of the 13 cases. At final review the retina was attached in 12 of the 13 cases. A final visual acuity of between 6/9 and 6/12 was achieved in six cases, four cases had acuity of between 6/18 and 6/24 and three cases had a visual result of less than 6/60.

High-voltage electron microscopy in eye research. Experimental analysis of the retinal pigment epithelium and choriocapillaris

The high-voltage electron microscope (HVEM) permits examination of sections much thicker (up to 1 micron) than those usually used in transmission electron microscopy, which are approximately 70 nm in thickness. Two examples of the utility of the HVEM in research on the ultrastructure of the retinal pigment epithelium (RPE) and choriocapillaris are given: the identification of intracytoplasmic tubules that arise from the basal plasma membrane of rat RPE cells; and the tracing of processes arising from choriocapillary endothelial cells during experimentally induced neovascularization. In each case HVEM provided information not easily obtained in routine thin sections.

The high prevalence of diabetes mellitus, impaired glucose tolerance and diabetic retinopathy in Nauru--the 1982 survey

A population survey in 1982 has confirmed that Nauruan adults suffer from an extremely high prevalence of Type 2 (noninsulin-dependent) diabetes mellitus. The crude population prevalence of Type 2 diabetes was 24%. Abnormal glucose tolerance (impaired glucose tolerance and diabetes) was present in over 40% of the adult population and exceeded 80% in both sexes after the age of 55 yr. Diabetic retinopathy was present in 24% of diabetic patients, confirming that this Micronesian population is susceptible to the microvascular consequences of hyperglycaemia. Subjects with impaired glucose tolerance had a prevalence of retinopathy three times that of normal subjects, though the difference did not reach statistical significance. Prevalence of retinopathy was substantially higher in diabetic patients than either normal subjects or those with impaired glucose tolerance.

Diabetic retinopathy in Nauruans

An epidemiologic survey of the whole adult Micronesian population of Nauru in the Central Pacific conducted in 1982 has confirmed that Nauruans, along with Pima Indians, suffer the highest rate of abnormal glucose tolerance yet recorded. To establish the morbid effects of hyperglycemia in this population, all responders to the diabetes survey were concurrently examined for diabetic retinopathy. In diabetic subjects, the crude prevalence of retinopathy was 24%. Specific rates were determined at various levels of the following characteristics: age, two-hour post-load plasma glucose, body mass index, duration of diabetes, and systolic blood pressure. Prevalence was found to rise with increasing two-hour plasma glucose and duration, to fall with increasing body mass index, and to have a quadratic relationship with age and systolic blood pressure. The multiple logistic regression model was used to determine whether the selected characteristics were significant in increasing the risk of retinopathy. Body mass index and systolic blood pressure did not contribute significantly to this risk after controlling for age. Increasing two-hour plasma glucose significantly increased the risk of retinopathy, and duration of disease was the strongest predictor variable. This study shows that the consequences of hyperglycemia in this Micronesian population are comparable to those already documented in European and American Indian communities.