Efficacy of sustained topical dorzolamide therapy for cystic macular lesions in patients with retinitis pigmentosa and usher syndrome

DEXAMETHASONE IMPLANT VERSUS TOPICAL CARBONIC ANHYDRASE INHIBITORS IN PATIENTS WITH BILATERAL RETINITIS PIGMENTOSA-RELATED CYSTOID MACULAR EDEMA: A Prospective, Paired-Eye Pilot Study

PURPOSE

To compare within-subject efficacy and safety of intravitreal dexamethasone implant and topical carbonic anhydrase inhibitors in the treatment of retinitis pigmentosa-related cystoid macular edema.

METHODS

Patients with bilateral retinitis pigmentosa-related cystoid macular edema were treated with intravitreal dexamethasone implant in one eye and topical carbonic anhydrase inhibitors in the contralateral eye. The primary endpoint was a change in central macular thickness. Secondary endpoints were changes in best-corrected visual acuity and microperimetric central retinal sensitivity. Intraocular pressure and other ocular complications were evaluated for safety assessment.

RESULTS

Nine patients were recruited for this 12-month follow-up study. Central macular thickness was significantly lower in intravitreal dexamethasone implant-treated eyes than in topical carbonic anhydrase inhibitors-treated eyes at Months 1 and 7, whereas mean best-corrected visual acuity was better in eyes treated with topical carbonic anhydrase inhibitors at Month 12 (borderline significant P = 0.0510). There was no difference in microperimetric sensitivity between the two treatments. Three patients developed ocular hypertension after intravitreal dexamethasone implant. Intravitreal dexamethasone implant showed an effect on the contralateral eye in five of nine patients.

CONCLUSION

Intravitreal dexamethasone implant was more effective than topical carbonic anhydrase inhibitors in reducing retinitis pigmentosa-related cystoid macular edema 1 month after treatment. Corticosteroids can play a key role in the management of retinitis pigmentosa-related cystoid macular edema; however, their routes, timing, and modes of administration should be further explored.

Carbonic anhydrase inhibitors limit complications in X-linked retinoschisis

Purpose

Carbonic anhydrase inhibitors (CAIs) reduce macular schisis in patients with X-linked retinoschisis (XLRS). The purpose of this study was to determine if CAIs reduce the incidence of complications from XLRS, including macular atrophy, retinal tears, and retinal detachment (RD), the most common causes of vision loss in patients with XLRS.

Methods

For this retrospective interventional case series, a chart review of patients examined at Cincinnati Children's Hospital Medical Center [CCHMC] and Cincinnati Eye Institute [CEI] between 1/1/2015 and 1/16/2023 was performed. Male patients were included based on genetically-confirmed RS1 or typical clinical presentation with known family history of XLRS with at least two follow-up visits.

Results

Twenty-eight patients (56 eyes) with XLRS were included. There were 10 RS1 variants among the 21 genotyped patients. Median age at clinical diagnosis was 10.4 years old (range: 0.4-55.7 years) with median follow-up time of 4.7 years (range: 0.2-38.3 years). Median presenting Snellen visual acuity was 20/60 (logMAR 0.48, range: 0.18-3). In 26 eyes of 15 patients treated with CAIs, median CST pre-treatment was 416 microns (range: 198-701 microns), and median percentage decrease in CST on treatment was 21.8% (range: 0-74.5%) from highest pre-treatment CST. Reduction in CST with CAI use was statistically significant (p = 0.02), but not logMAR VA (p = 0.64). There was no significant difference in CST between patients treated with topical vs. oral CAI (p = 0.95) or between patients with partial or complete CAI adherence (p = 0.60). Ten eyes of seven patients had an RD requiring surgical intervention. No treated eyes developed new macular atrophy, peripheral retinoschisis, retinal tears, or RD; two eyes on topical CAIs had spontaneous resolution of bullous peripheral retinoschisis.

Conclusion

During the follow-up period, patients taking CAIs reduced macular schisis and did not experience new complications of macular atrophy, retinal tears, or RD. This is a relatively large cohort with long-term follow-up periods for patients with XLRS. Reduced macular schisis may not require perfect adherence with CAIs. A large, prospective, randomized, controlled clinical trial is needed to determine the potential of CAIs to improve visual function, reduce retinoschisis, and prevent RD.

Oral minocycline for the treatment of retinitis pigmentosa-associated cystoid macular edema: results of a phase I/II clinical trial

PURPOSE

The etiology of retinitis pigmentosa (RP)-associated cystoid macular edema (CME) has been related to retinal neuroinflammation and microglial activation. Minocycline, a drug FDA-approved for anti-microbial indications, also inhibits microglial activation and expression of inflammatory mediators. This study investigates the safety and efficacy of oral minocycline as primary treatment for RP-associated CME.

METHODS

A single-center, prospective, open-label phase I/II clinical trial enrolled five participants with RP-associated CME. Participants had lead-in assessments prior to the initiation of oral minocycline 100 mg twice daily for 12 months. Main outcome variables included changes in best-corrected visual acuity (BCVA) and retinal central subfield thickness (CST) measured using spectral domain optical coherence tomography relative to mean of pre-treatment measurements.

RESULTS

The study drug was well tolerated and not associated with any severe adverse events. No significant changes in mean BCVA from study baseline were noted in either the study eye (+ 0.7 ± 4.1 letters at 6 months, - 1.1 ± 1.7 letters at 12 months) or the qualifying fellow eye (- 0.3 ± 3.4 letters at 6 months, - 0.3 ± 4.6 letters at 12 months) (p > 0.05 for all comparisons). Mean percentage changes in CST from baseline however decreased progressively with treatment (decreases at 6 and 12 months: study eyes 3.9 and 9.8%; qualifying fellow eyes 1.4 and 7.7%). Considering all eyes (n = 10), mean percentage CST decrease at 6 and 12 months was 2.7 ± 9.5% (p = 0.39) and 8.7 ± 9.5% (p = 0.02) respectively.

CONCLUSION

Oral minocycline administration over 12 months was associated with no significant changes in mean BCVA and a small but progressive decrease in mean CST.

TRIAL REGISTRATION

NCT02140164 (05/2014).

Usher Syndrome on the Island of Ireland: A Genotype-Phenotype Review

Purpose

Usher syndrome (USH) is a genetically heterogeneous group of autosomal recessive (AR) syndromic inherited retinal degenerations (IRDs) representing 50% of deaf-blindness. All subtypes include retinitis pigmentosa, sensorineural hearing loss, and vestibular abnormalities. Thorough phenotyping may facilitate genetic diagnosis and intervention. Here we report the clinical/genetic features of an Irish USH cohort.

Methods

USH patients were selected from the Irish IRD registry (Target 5000). Patients were examined clinically (deep-phenotyping) and genetically using a 254 IRD-associated gene target capture sequencing panel, USH2A exon, and whole genome sequencing.

Results

The study identified 145 patients (24.1% USH1 [n = 35], 73.8% USH2 [n = 107], 1.4% USH3 [n = 2], and 0.7% USH4 [n = 1]). A genetic diagnosis was reached in 82.1%, the majority (80.7%) being MYO7A or USH2A genotypes. Mean visual acuity and visual field (VF) were 0.47 ± 0.58 LogMAR and 31.3° ± 32.8°, respectively, at a mean age of 43 years. Legal blindness criteria were met in 40.7%. Cataract was present in 77.4%. ADGRV1 genotypes had the most VF loss, whereas USH2A patients had greater myopia and CDH23 had the most astigmatism. Variants absent from gnomAD non-Finnish Europeans and ClinVar represented more than 20% of the variants identified and were detected in ADGRV1, ARSG, CDH23, MYO7A, and USH2A.

Conclusions

USH is a genetically diverse group of AR IRDs that have a profound impact on affected individuals and their families. The prevalence and phenotype/genotype characteristics of USH in Ireland have, as yet, gone unreported. Understanding the genotype of Irish USH patients may guide clinical and genetic characterization facilitating access to existing/novel therapeutics.

Topical Treatment for Retinal Degenerative Pathologies: A Systematic Review

The topical administration of medicines is the preferred route in ocular therapy, at least for the anterior segment of the eye. However, the eye's inherent functional and biological barriers all work against the active pharmaceutical ingredient (API) to efficiently reach the targeted retinal structures. The main objective of this article is to offer a systematic review of the scientific literature in recent years, focusing on the latest developments of topical treatment intended for retinal degenerative diseases. Database search returned 102 clinical studies, focused on topical treatment for age macular degeneration, macular edemas (in diabetic retinopathy, surgery related or in retinal dystrophies) or glaucoma. After the exclusion of low-powered studies and those combining vitreo-retinal surgery, 35 articles remained for analysis. Currently, the topical treatment of retinal degenerative diseases is limited by the difficulty to deliver effective drug concentrations to the posterior eye structures. However, in the case of drug classes like NSAIDs, the presence of certain molecular and metabolic features for specific representatives makes the topical administration currently feasible in several clinical contexts. For other drug classes, either a fine-tuning of the API's pharmacokinetic profile or the use of more advanced formulation strategies, such as rationally designed nanostructured drugs and vehicles, crystalline polymorphs or supramolecular complexes, could bring the much awaited breakthrough for a more predictable and controlled delivery towards the retinal structures and could eventually be employed in the future for the development of more effective ways of delivering drugs to the posterior eye, with the ultimate goal of improving their clinical efficacy.

Retinitis Pigmentosa: Current Clinical Management and Emerging Therapies

Retinitis pigmentosa (RP) comprises a group of inherited retinal dystrophies characterized by the degeneration of rod photoreceptors, followed by the degeneration of cone photoreceptors. As a result of photoreceptor degeneration, affected individuals experience gradual loss of visual function, with primary symptoms of progressive nyctalopia, constricted visual fields and, ultimately, central vision loss. The onset, severity and clinical course of RP shows great variability and unpredictability, with most patients already experiencing some degree of visual disability in childhood. While RP is currently untreatable for the majority of patients, significant efforts have been made in the development of genetic therapies, which offer new hope for treatment for patients affected by inherited retinal dystrophies. In this exciting era of emerging gene therapies, it remains imperative to continue supporting patients with RP using all available options to manage their condition. Patients with RP experience a wide variety of physical, mental and social-emotional difficulties during their lifetime, of which some require timely intervention. This review aims to familiarize readers with clinical management options that are currently available for patients with RP.

Management of Cystoid Macular Edema in Retinitis Pigmentosa: A Systematic Review and Meta-Analysis

Background

To date, various treatments for cystoid macular edema (CME) in retinitis pigmentosa (RP) have been reported. We performed a systematic review and meta-analysis to evaluate the efficacy and safety of current treatments for RP-CME.

Methods

PubMed, Embase and the Cochrane library were searched from inception to August 2021. ClinicalTrials.gov, WHO ICTRP and ISRCTN were also searched for relevant studies. Only studies published in English were included. The RoB 2 tool was used to evaluate the risk of bias of randomized controlled trials (RCTs), and the MINORS scale was used to assess the methodological quality of non-RCTs. Review manager (Revman) was used to pool the data. The primary outcomes included the change of central macular thickness (CMT) and best-corrected visual acuity (BCVA) from baseline. The secondary outcomes included fluorescein angiography (FA) leakage, rebound of CME and adverse effects.

Results

Thirty-two studies were included in the current systematic review and 7 studies were used for meta-analysis. Treatments for RP-CME included oral and topical carbonic anhydrase inhibitors (CAIs), systematic and local steroids, anti-VEGF therapy, NSAIDS, grid LASER photocoagulation, subliminal micropulse LASER, vitrectomy, lutein supplement and oral minocycline. CAIs and local steroids were proved to be effective in reducing CMT. The effects of anti-VEGF reagents varied among studies. Regarding other treatments, only one study for each method fitted the inclusion criteria, so the evidence was very limited.

Conclusion

Topical CAIs, oral CAIs and local steroids are effective in treating RP-CME. However, due to the overall inferior design and small patient number of the included studies, the quality of evidence was poor. Systematic steroids, LASER, NSAIDS and vitrectomy may also be effective, nevertheless, considering the limited number of studies, no conclusion could be drawn regarding these treatments. More well-designed and conducted studies are needed in this field.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021273979, identifier CRD42021273979.

EFFECT OF ORAL CARBONIC ANHYDRASE INHIBITOR ON CYSTOID MACULAR EDEMA ASSOCIATED WITH RETINITIS PIGMENTOSA: an OCT and OCT angiography study

PURPOSE

To investigate the factors associated with visual improvement in response to oral carbonic anhydrase inhibitors (CAIs) and the occurrence of microvascular changes in patients with retinitis pigmentosa-associated cystoid macular edema (RP-CME).

METHODS

This retrospective cohort study included 59 eyes from 39 patients with RP-CME who underwent at least 3 month of oral CAI treatment. The eyes were divided into responding and non-responding groups based on optical coherence tomography (OCT) criteria (resolution of cyst and reduction of foveal or parafoveal volume). All eyes were assessed before and after treatment using OCT and OCT angiography.

RESULTS

Thirty-three eyes (55.9%) demonstrated a positive response to treatment, and 26 eyes (44.1%) did not. Compared with non-responding eyes, responding eyes had a significantly higher frequency of multilayer CME than CME limited to the inner nuclear layer (P = 0.016). Subgroup analysis within the responding group revealed that improvements in visual acuity were more likely in eyes with fovea-involving CME and a higher baseline external limiting membrane and ellipsoid zone width. Microvascular parameters showed no significant changes after treatment.

CONCLUSION

Eyes with CME extending to the ONL or central fovea, and higher initial photoreceptor integrity may be prognostic factors associated with structural and functional improvements after CAI treatment. Early treatment of multilayer CME with foveal involvement seems to be crucial in preventing irreversible photoreceptor damage.

Frequency of cystoid macular edema and vitreomacular interface disorders in genetically solved syndromic and non-syndromic retinitis pigmentosa

PURPOSE

Retinitis pigmentosa (RP) corresponds to a group of inherited retinal disorders where progressive rod-cone degeneration is observed. Cystoid macular edema (CME) and vitreomacular interface disorders (VMID) are known to complicate the RP phenotype, challenging an age-old concept of retained central visual acuity. The reported prevalence of these changes varies greatly among different studies. We aim to describe the frequency of CME and VMID and identify predictors of these changes in a cohort of Caucasian patients with genetically solved syndromic (sRP) and non-syndromic RP (nsRP).

METHODS

Cross-sectional study of patients with genetically solved sRP or nsRP. Genetic testing was clinically oriented in all probands and coordinated by a medical geneticist. The presence/absence of CME and VMIDs such as epiretinal membrane (ERM), vitreomacular traction (VMT), lamellar hole (LH), macular hole (MH), and macular pseudohole (MPH), and the integrity of the neurosensory retina and retinal pigment epithelium were evaluated in individual macular SD-OCT b-scans. Mixed-effects regression analysis models were used to identify significant predictors of BCVA, CME, and VMID. Significance was considered at α < 0.05.

RESULTS

We included 250 eyes from 125 patients. Mean age was 44.9 ± 15.7 years and 55.2% were male. Eighty-eight patients had nsRP and 37 had sRP. Median BCVA was 0.5 (0.2-1.3) logMAR. CME was found in 17.1% of eyes, while ERM was found in 54.3% of eyes. The frequency of CME (p = 0.45) and ERM (p = 0.07) did not differ between sRP and nsRP patients, nor across different inheritance patterns. Mixed-effects univariate linear regression identified age (p = 0.04), cataract surgery (p < 0.01), and loss of integrity of outer retinal layers (p < 0.01) as significant predictors of lower visual acuity, while increased foveal thickness (p < 0.01) and the presence of CME (p = 0.04) were predictors of higher visual acuity. On mixed-effects multivariable analysis, only increased foveal thickness was significantly associated with better visual acuity (p < 0.01).

CONCLUSION

We found that the burden of ERM and CME in RP patients is high, highlighting the importance of screening for these potentially treatable conditions to improve the quality of life of RP patients.

Carbonic anhydrase inhibitors in the management of macular edema: A review of the literature

Background

Macular edema (ME) is a vision-threatening condition that commonly develops as a consequence of ocular diseases, including age-related macular degeneration, retinal vaso-occlusion of the central retinal vein and its branches, diabetic retinopathy, central serous chorioretinopathy, uveitis, retinitis pigmentosa, pseudophakia, ocular trauma, and drug toxicity. The treatment of ME remains challenging, although steroids and vascular endothelial growth factor inhibitors are available. Cost-effective therapy using a noninvasive administration route is required. This study aimed at reviewing the role of carbonic anhydrase inhibitors (CAIs) in the management of ME.

Methods

A literature search was conducted using PubMed/MEDLINE and Google Scholar for studies from January 2000 to March 2022. The following keywords were used in various combinations: "macular edema", "carbonic anhydrase", "carbonic anhydrase inhibitors", "acetazolamide", "dorzolamide", and "brinzolamide".

Results

Articles with high or medium clinical relevance were selected for this review. We found that multiple studies have demonstrated the relevance and efficacy rates of CAIs in the management of ME. Most published studies focused on acetazolamide and dorzolamide, with nearly all studies reporting therapeutic responses.

Conclusions

ME is the leading cause of vision loss and requires noninvasive and cost-effective pharmacotherapy. With progress in the understanding of ME, particularly the role of carbonic anhydrase as a key driver, CAIs are the focus of research. Further optimization of the choice of CAIs and retinal bioavailability, potentially with nanoparticle formulations, is required to enable the effective management of ME. Further research is warranted to address the therapeutic effects of CAIs in different formulations.

Aqueous eye drops containing drug/cyclodextrin nanoparticles deliver therapeutic drug concentrations to both anterior and posterior segment

Using topical application to deliver therapeutic concentrations of drugs to the posterior segment of the eye remains very challenging. As a result, posterior segment diseases are usually treated by intravitreal injection or implant. While topical treatments are commonly used for anterior segment conditions, they sometimes require frequent applications. Eye drop formulations based on γ-cyclodextrin (γCD)-based nanoparticle aggregates were developed, which in animal models and clinical studies deliver therapeutic concentrations of drugs (dorzolamide and dexamethasone) to both anterior and posterior segments of the eye. An early study in humans showed dorzolamide/γCD eye drops could achieve comparable intraocular pressure decreases to commercial dorzolamide eye drops, but with less frequent application. Pilot studies with dexamethasone/γCD eye drops suggested that they could be effective in a range of conditions, including diabetic macular oedema, cystoid macular oedema and vitritis secondary to uveitis, postcataract surgery inflammation and postoperative treatment in trabeculectomy. Phase II studies with similar dexamethasone/γCD nanoparticle eye drops in diabetic macular oedema and postcataract surgery inflammation have recently been completed. This technology has the potential to be used with other classes of drug molecules and to replace or complement invasive treatments, providing safer, non-invasive therapies, particularly for posterior segment conditions, that can be self-administered as eye drops by patients.

TOPICAL DORZOLAMIDE FOR CYSTOID MACULAR EDEMA IN BIETTI CRYSTALLINE RETINAL DYSTROPHY

PURPOSE

To report a case of Bietti crystalline retinal dystrophy with cystoid macular edema (CME) that was successfully treated with topical carbonic anhydrase inhibitor.

METHODS

A 35-year-old otherwise healthy woman, with a known case of Bietti crystalline retinal dystrophy, presented with progressive visual impairment in her right eye for 3 months. The best-corrected visual acuity was 20/50 in the right eye and 20/25 in the left eye. On the basis of the multimodal imaging findings, the patient was diagnosed with Bietti crystalline retinal dystrophy with unilateral CME. Carbonic anhydrase inhibitor therapy twice a day was initiated.

RESULTS

Three months later, visual acuity improved to 20/25 in the right eye, and CME had resolved based on spectral domain ocular coherence tomography findings, although the CME reoccurred after discontinuation of the drug. Three months after resuming the therapy, the best-corrected visual acuity improved back to 20/25.

CONCLUSION

Cystoid macular edema is one of the main causes of central visual worsening in patients with Bietti crystalline retinal dystrophy. This complication may be resolved with topical carbonic anhydrase inhibitor, resulting in improved anatomical and visual outcomes.

Anti-VEGF-Resistant Retinal Diseases: A Review of the Latest Treatment Options

Anti-vascular endothelial growth factor (anti-VEGF) therapy currently plays a central role in the treatment of numerous retinal diseases, most notably exudative age-related macular degeneration (eAMD), diabetic retinopathy and retinal vein occlusions. While offering significant functional and anatomic benefits in most patients, there exists a subset of 15–40% of eyes that fail to respond or only partially respond. For these cases, various treatment options have been explored with a range of outcomes. These options include steroid injections, laser treatment (both thermal therapy for retinal vascular diseases and photodynamic therapy for eAMD), abbreviated anti-VEGF treatment intervals, switching anti-VEGF agents and topical medications. In this article, we review the effectiveness of these treatment options along with a discussion of the current research into future directions for anti-VEGF-resistant eyes.

Retinal Dystrophies and the Road to Treatment: Clinical Requirements and Considerations

: Retinal dystrophies (RDs) comprise relatively rare but devastating causes of progressive vision loss. They represent a spectrum of diseases with marked genetic and clinical heterogeneity. Mutations in the same gene may lead to different diagnoses, for example, retinitis pigmentosa or cone dystrophy. Conversely, mutations in different genes may lead to the same phenotype. The age at symptom onset, and the rate and characteristics of peripheral and central vision decline, may vary widely per disease group and even within families. For most RD cases, no effective treatment is currently available. However, preclinical studies and phase I/II/III gene therapy trials are ongoing for several RD subtypes, and recently the first retinal gene therapy has been approved by the US Food and Drug Administration for RPE65-associated RDs: voretigene neparvovec-rzyl (Luxturna). With the rapid advances in gene therapy studies, insight into the phenotypic spectrum and long-term disease course is crucial information for several RD types. The vast clinical heterogeneity presents another important challenge in the evaluation of potential efficacy in future treatment trials, and in establishing treatment candidacy criteria. This perspective describes these challenges, providing detailed clinical descriptions of several forms of RD that are caused by genes of interest for ongoing and future gene or cell-based therapy trials. Several ongoing and future treatment options will be described.

A rare case of type 3 usher syndrome with bilateral cystoid macular edema treated with topical dorzolamide

A 30-year-old female presented with gradually progressive diminution of vision for 1 month, with night blindness for the past 5 years and difficulty in hearing for the past 10 years. Her developmental history and family history were unremarkable. Ocular examination revealed visual acuity of 6/36 in both eyes. Fundus showed features of retinitis pigmentosa with bilateral macular edema. Audiometry revealed bilateral sensorineural hearing loss; although, her vestibular functions were preserved. Clinical diagnosis of Usher syndrome type 3 was made based on normal hearing at birth, delayed presentation of progressive visual and auditory impairment with normal vestibular function, and developmental milestones. Her macular edema resolved after 3 months of treatment with topical dorzolamide therapy. The unique feature of this case is the presence of bilateral macular edema in type 3 Usher syndrome, which is rarely reported in literature.

A RANDOMIZED PAIRED-EYE TRIAL OF INTRAVITREAL DEXAMETHASONE IMPLANT FOR CYSTOID MACULAR EDEMA IN RETINITIS PIGMENTOSA

PURPOSE

To evaluate the efficacy and safety of intravitreal dexamethasone (DEX) implant in retinitis pigmentosa patients with cystoid macular edema (CME).

METHODS

In this randomized, noncontrolled, paired-eye, single crossover clinical trial, one eye of retinitis pigmentosa patients with bilateral CME with central macular thickness of >250 µm was randomized to intravitreal DEX implant while the fellow eye was observed. Both eyes were started on topical dorzolamide. At Month 6, DEX implant was eligible for both eyes when CME was >250 µm. Patients were followed up until Month 12. Primary outcome measures were the central macular thickness and best-corrected visual acuity changes from baseline at Month 2.

RESULTS

Fourteen patients with bilateral RP-CME were included. Study eyes showed significant central macular thickness decrease (median, -147.5 µm; P = 0.001) and best-corrected visual acuity improvement (median, +6 letters; P = 0.001) at Month 2, but not at Month 6. Intravitreal DEX implant at Month 6 produced comparable efficacy to baseline treatment in 11 fellow eyes and 12 study eyes. Topical dorzolamide did not show significant therapeutic efficacy. During 12 months, elevated intraocular pressure of >21 mmHg and cataract progression were observed in 14.3% and 40.0% of study eyes.

CONCLUSION

Intravitreal DEX implant can both reduce macular thickness and improve vision in RP-CME, while repeated injection is required.

Management of Idiopathic Macular Telangiectasia Type 2

Macular telangiectasia type 2 (MacTel) is a relatively rare disease without established treatments. Although MacTel was previously considered a primarily vascular condition, the thinking on its pathogenesis has shifted to it now being considered principally a neurodegenerative disease. This has resulted in a subsequent change in the approach to treatment toward neuro-protection for the non-proliferative phase of this disease. Carotenoid supplementation has had mixed results. Ciliary neurotrophic factor (CNTF) has demonstrated some promising early results, but further study is necessary to determine its actual effect. Some structural improvements have been seen in the non-proliferative phase with oral acetazolamide but without accompanying functional improvement. Anti-vascular endothelial drugs have been studied and not found to have benefit in the non-proliferative phase of disease but have demonstrated significant structural and functional value in the treatment of secondary neovascularization. There is no level I evidence for the various proposed MacTel treatments, and efforts need to be directed toward conducting multicenter randomized trials to better understand possible treatments for this condition.

Retrospective cohort study exploring whether an association exists between spatial distribution of cystoid spaces in cystoid macular oedema secondary to retinitis pigmentosa and response to treatment with carbonic anhydrase inhibitors

BACKGROUND

Carbonic anhydrase inhibitors (CAIs) are frequently used as an initial step to treat retinitis pigmentosa-associated cystoid macular oedema (RP-CMO). Interestingly, it has been postulated that CAIs might reduce outer nuclear layer (ONL) fluid more effectively than inner nuclear layer (INL) fluid due to better access to retinal pigment epithelium basolateral membrane than neurosensory retina. This retrospective cohort study explores if an association between spatial distribution of cystoid spaces in RP-CMO and CAI response exists.

METHODS

Two independent graders reviewed pretreatment and post-treatment optical coherence tomography (OCT) images of 25 patients (43 eyes) initiated on topical and/or oral CAIs between January 2013 and December 2014. Documentation included the presence/absence of fluid (and layer(s) involved), external limiting membrane, epiretinal membrane (ERM), vitreomacular adhesion/traction, lamellar/full-thickness macular hole and central macular thickness (CMT)/volume.

RESULTS

INL fluid was found in all study eyes. All 13 'responders' (at least 11% reduction of CMT after treatment) demonstrated pretreatment ONL fluid. In seven patients (four responders and three non-responders), complete clearance of ONL fluid was achieved despite persistence of INL fluid. ERM presence was similar in responders and non-responders.

CONCLUSION

In this study, INL fluid was found to be the most common spatial distribution of RP-CMO. However, patients who were classed as a 'responder' to CAI treatment all demonstrated coexisting ONL fluid on their pretreatment OCT scans. This may be explained by CAIs having better access to retinal pigment epithelium basolateral membrane than neurosensory retina. Our study also suggests a minimal impact on response to CAIs by ERM.

Efficacy of carbonic anhydrase inhibitors in management of cystoid macular edema in retinitis pigmentosa: A meta-analysis

Background

Carbonic anhydrase inhibitors (CAI) are often used in the treatment of cystoid macular edema (CME) in retinitis pigmentosa (RP) patients. The aim of this meta-analysis is to gain a better understanding of the overall efficacy of CAI treatment.

Methods

Databases including PubMed, EMBASE, and Cochrane Library were searched to identify relevant studies. Eligible studies were clinical trials of patients with RP assigned topical or oral CAIs such as dorzolamide and acetazolamide. Changes in central macular thickness (CMT) by OCT in μm and best-corrected visual acuity (BCVA) in log MAR equivalents were extracted and results compared between baseline and after treatment.

Results

11 clinical reports were identified which included a total of 194 patients (358 eyes) available for analysis, with 59 patients (115 eyes) assigned oral CAI treatment and 135 patients (243 eyes) assigned topical CAI treatment. The combined results showed a significant reduction of macular edema, as calculated by baseline and final central macular thickness (CMT) based on OCT examination (46.02μm, 95%CI: -60.96, -31.08, I² = 65%). However, the effect on visual acuity was inconsistent across studies.

Conclusion

Based on non randomized controlled clinical studies, RP patients with CME who were treated with CAIs had better anatomical outcomes, but the effect on visual acuity was contradictory across studies. Multicenter prospective randomized controlled trials would be ideal to definitively test its clinical efficacy in RP patients.

Pharmacokinetic aspects of retinal drug delivery

Drug delivery to the posterior eye segment is an important challenge in ophthalmology, because many diseases affect the retina and choroid leading to impaired vision or blindness. Currently, intravitreal injections are the method of choice to administer drugs to the retina, but this approach is applicable only in selected cases (e.g. anti-VEGF antibodies and soluble receptors). There are two basic approaches that can be adopted to improve retinal drug delivery: prolonged and/or retina targeted delivery of intravitreal drugs and use of other routes of drug administration, such as periocular, suprachoroidal, sub-retinal, systemic, or topical. Properties of the administration route, drug and delivery system determine the efficacy and safety of these approaches. Pharmacokinetic and pharmacodynamic factors determine the required dosing rates and doses that are needed for drug action. In addition, tolerability factors limit the use of many materials in ocular drug delivery. This review article provides a critical discussion of retinal drug delivery, particularly from the pharmacokinetic point of view. This article does not include an extensive review of drug delivery technologies, because they have already been reviewed several times recently. Instead, we aim to provide a systematic and quantitative view on the pharmacokinetic factors in drug delivery to the posterior eye segment. This review is based on the literature and unpublished data from the authors' laboratory.

Retinitis pigmentosa-associated cystoid macular oedema: pathogenesis and avenues of intervention

Hereditary retinal diseases are now the leading cause of blindness certification in the working age population (age 16–64 years) in England and Wales, of which retinitis pigmentosa (RP) is the most common disorder. RP may be complicated by cystoid macular oedema (CMO), causing a reduction of central vision. The underlying pathogenesis of RP-associated CMO (RP-CMO) remains uncertain, however, several mechanisms have been proposed, including: (1) breakdown of the blood-retinal barrier, (2) failure (or dysfunction) of the pumping mechanism in the retinal pigment epithelial, (3) Müller cell oedema and dysfunction, (4) antiretinal antibodies and (5) vitreous traction. There are limited data on efficacy of treatments for RP-CMO. Treatments attempted to date include oral and topical carbonic anhydrase inhibitors, oral, topical, intravitreal and periocular steroids, topical non-steroidal anti-inflammatory medications, photocoagulation, vitrectomy with internal limiting membrane peel, oral lutein and intravitreal antivascular endothelial growth factor injections. This review summarises the evidence supporting these treatment modalities. Successful management of RP-CMO should aim to improve both quality and quantity of vision in the short term and may also slow central vision loss over time.

Topical carbonic anhydrase inhibitors in macular edema associated with Alström syndrome

BACKGROUND

Alström syndrome is a rare genetic ciliopathy caused by a mutation in the ALMS1 gene. The syndrome is characterized by cone-rod dystrophy, dilated myocardiopathy, childhood obesity and sensorineural hearing loss. To date, cystoid macular edema has not been reported.

METHODS

A female affected by Alström syndrome developed bilateral cystoid macular edema evidenced by optical coherence tomography. A topical carbonic anhydrase inhibitor was prescribed.

RESULTS

Complete resolution of the cystoid macular edema was achieved, though visual acuity did not improve.

CONCLUSIONS

Topical carbonic anhydrase inhibitors may have a role in the treatment of macular edema in syndromic retinal dystrophies such as Alström syndrome.

USE OF AFLIBERCEPT FOR THE MANAGEMENT OF REFRACTORY PSEUDOPHAKIC MACULAR EDEMA IN IRVINE-GASS SYNDROME AND LITERATURE REVIEW

BACKGROUND/PURPOSE

To present the patient treated for pseudophakic cystoid macular edema with intravitreal aflibercept.

METHODS

Interventional case report.

CASE

An 83-year-old woman presented with decreased vision 1 month after uneventful cataract surgery. After failure to respond to posterior subtenons triamcinolone and three Ranibizumab injections, the patient responded to one intravitreal aflibercept injection. Recurrence occurred two months later, and therefore three monthly injections were then given. Again the patient responded although recurrence occurred two months after treatment. The patient refused further treatment.

CONCLUSION

Intravitreal aflibercept may be effective for the treatment of pseudophakic cystoid macular edema.

Photocoagulation of human retinal pigment epithelium in vitro: unravelling the effects on ARPE-19 by transcriptomics and proteomics

PURPOSE

Despite the extensive use of retinal photocoagulation for ischaemia and vascular leakage in retinal vascular disease, the molecular mechanisms behind its clinical beneficial effects are still poorly understood. One important target of laser irradiation is the retinal pigment epithelium (RPE). In this study, we aimed at identifying the isolated effects of photocoagulation of RPE at both the mRNA and protein expression levels.

METHODS

Human ARPE-19 cells were exposed to photocoagulation. Gene expression and protein expression were compared to untreated cells using microarray and liquid chromatography-mass spectrometry analysis. Genes and proteins queried by microarray and mass spectrometry were subjected to the Kyoto Encyclopedia of Genes and Genomes (KEGG) database pathway analyses.

RESULTS

Laser irradiation resulted in an induction of the cytoprotective heat-shock protein subfamily Hsp70 as well as in a suppression of the vascular permeability factor carbonic anhydrase 9 (CA9). These expression patterns were evident at both the mRNA and protein levels. KEGG pathway analyses revealed genes and proteins involved in cellular turnover, repair and inflammation.

CONCLUSIONS

By characterizing the transcriptional and translational effects of laser coagulation on the RPE cells in culture, we have revealed responses, which might contribute to some of the beneficial effects obtained by photocoagulation for ischaemia and vascular leakage in retinal vascular disease.

[Efficacy of dorzolamide in reducing retinal thickness after photocoagulation in diabetic macular oedema]

BACKGROUND

Focal photocoagulation interrupts vascular leakage in diabetic macular edema, and allows the retinal pigment epithelium to withdraw fluid that thickens the retina; this mechanism could be enhanced by dorzolamida, a topical carbonic anhydrase inhibitor.

OBJECTIVE

To determine the efficacy of dorzolamida compared against placebo, in reducing retinal thickness after focal photocoagulation, in eyes with diabetic macular oedema.

MATERIAL AND METHODS

Experimental, comparative, prospective, longitudinal, double blind study in diabetics with focal macular oedema treated with photocoagulation. Treated eyes were randomly assigned three weeks after the procedure to receive dorzolamide (group 1) or placebo (group 2), three times daily during three weeks. Means of visual acuity, center point thickness and macular volume were compared 3 and 6 weeks after photocoagulation within groups (Wilcoxon's t) and between groups (Mann-Whitneys's U).

RESULTS

Sixty-nine eyes form patients aged 58.3 ± 8.3 years; 37 were assigned to group 1 and 42 to group 2. Mean center point thickness changed from 178.4 ± 34μm to 170 ± 29.1μm in group 1 (p = 0.04), and from 179.2 ± 22.4μm to 178.6 ± 20.8μm in group 2 (p = 0.7); mean macular volume changed from 7.63 ± 0.52mm(3) to 7.50 ± 0.50mm(3) in group 1 (p = 0.02) and from 7.82 ± 0.43mm(3) to 7.76 ± 0.42mm(3) in group 2 (p = 0.014).

CONCLUSIONS

The efficacy of dorzolamide was higher than that of placebo, to reduce retinal thickness after focal photocoagulation in diabetics with macular oedema.

Nanotherapies for the treatment of ocular diseases

The topical route is the most frequent and preferred way to deliver drugs to the eye. Unfortunately, the very low ocular drug bioavailability (less than 5%) associated with this modality of administration, makes the efficient treatment of several ocular diseases a significant challenge. In the last decades, it has been shown that specific nanocarriers can interact with the ocular mucosa, thereby increasing the retention time of the associated drug onto the eye, as well as its permeability across the corneal and conjunctival epithelium. In this review, we comparatively analyze the mechanism of action and specific potential of the most studied nano-drug delivery carriers. In addition, we present the success achieved until now using a number of nanotherapies for the treatment of the most prevalent ocular pathologies, such as infections, inflammation, dry eye, glaucoma, and retinopathies.

Efficacy of topical dorzolamide therapy for cystoid macular edema in a patient with MFRP-related nanophthalmos-retinitis pigmentosa-foveoschisis-optic disk drusen syndrome

PURPOSE

Mutations in the MFRP (membrane-type frizzled-related protein) gene leads to an entity characterized by retinitis pigmentosa, nanophthalmos, optic disk drusen, and macular changes, originally described as foveoschisis. Despite the association of MFRP gene mutation and increase in macular thickness, no treatment modality has been described for cystoid macular edema related to this particular entity so far.

METHODS

In this case report, a 52-year-old woman presented with nanophthalmos, optic disk drusen, retinitis pigmentosa, and increase in macular thickness. Genetic analysis revealed an MFRP gene mutation. The patient was treated with topical carbonic anhydrase inhibitors.

RESULTS

A progressive decrease in macular thickness and cystic changes was observed during the 2-month course of topical carbonic anhydrase inhibitor treatment, and best-corrected visual acuity improved from 20/100 to 20/50. Macular thickness remained stable after 6 months of follow-up.

CONCLUSION

Cystoid macular edema is part of the macular changes noted in the MFRP mutation-related nanophthalmos-retinitis pigmentosa-foveoschisis-optic disk drusen, syndrome. Taking into account that resolution of cystoid macular edema in patients with retinitis pigmentosa may delay an irreversible decrease in visual acuity, treatment should be considered when cystic changes are suspected. Topical carbonic anhydrase inhibitor was effective in decreasing macular thickness and cystic changes in the patient reported.

Comparison of topical dorzolamide and ketorolac treatment for cystoid macular edema in retinitis pigmentosa and Usher's syndrome

PURPOSE

To investigate the topical effect of dorzolamide versus ketorolac on retinitis pigmentosa (RP) and Usher's syndrome (US) macular edema.

METHODS

Prospective, randomized and interventional study. A total of 28 eyes of 18 patients were included. Five eyes had US, 23 had RP. Fifteen eyes were allocated to ketorolac tromethamine 0.5% (4 drops daily regimen) and 13 eyes to dorzolamide hydrochloride 2% (3 drops daily regimen) treatment groups. Snellen's best-corrected visual acuity (BCVA), foveal thickness (FT) and foveal zone thickness (FZT) measured by Stratus® optical coherence tomography (OCT) were evaluated at baseline, 1, 3, 6 and 12 months after treatment.

RESULTS

Patients assigned to ketorolac had a baseline BCVA of 0.37 ± 0.17 logMAR which improved at the end of 1 year to 0.28 ± 0.16 (p = 0.02). Three eyes (20%) of 2 patients improved by 7 letters or more. Mean FT and FZT did not change significantly during the study follow-up. After 1 year of treatment, 4 eyes (27%) of 3 patients showed an improvement of at least 16% of FT and 11% of FZT. Patients assigned to dorzolamide had a baseline BCVA of 0.48 ± 0.34 logMAR which improved in the first 6 months (0.40 ± 0.30; p = 0.01), with a decrease at 1 year (0.42 ± 0.27; p = 0.20). Seven eyes (54%) of 5 patients had an improvement of 7 letters or more. Mean FT and FZT did not change significantly either. After 1 year of treatment, 3 eyes (23%) of 2 patients showed an improvement of at least 16% on FT and 11% on FZT.

CONCLUSIONS

RESULTS suggest that dorzolamide and ketorolac might improve visual acuity and therefore be of interest in selected cases. No relationship between retinal thickness fluctuation and visual acuity was found. Sample size was a limitation to the study.

Macular retinal detachment associated with intrachoroidal cavitation in myopic patients

PURPOSE

To investigate the clinical characteristics and treatment outcomes of macular retinal detachment (MRD) associated with intrachoroidal cavitation (ICC) in myopic patients.

METHODS

In this retrospective, consecutive, interventional case series, five patients with ICC and associated MRD were enrolled from January 2005 to December 2012. Basic ocular characteristics and clinical appearances of their ICC and MRD were recorded. Individual treatment courses were assessed with fundus photographs and serial optical coherence tomography.

RESULTS

The average age and refraction were 43.8 ± 11.0 years old and -9.37 ± 2.73 diopters, respectively. Initial BCVA ranged from 20/100 to 20/30. Definite communication between the ICC and the subretinal space was noted in one case, suspected curvilinear communication in two cases, and between the peripapillary area and the subretinal space in two cases. Two cases received intravitreal injection of perfluoropropane and peripapillary laser; subretinal fluid (SRF) resolved in one and decreased in the other. One case had SRF reabsorbed after prolonged use of topical carbonic anhydrase inhibitor.

CONCLUSIONS

ICC in high myopic patients may be associated with MRD. There might be communication between the ICC and the subretinal space. Intravitreal injection of an expansile gas may be beneficial, but the best treatment remains undetermined.

Dorzolamide chlorhydrate versus acetazolamide in the management of chronic macular edema in patients with retinitis pigmentosa: description of three case reports

AIMS

To assess the efficacy of topical dorzolamide for treating cystoid macular edema in patients with retinitis pigmentosa and minimize the secondary effects of maintenance therapy in patients with retinitis pigmentosa (RP) who present with chronic microcystic macular edema.

METHODS

To replace acetazolamide systemic treatment, with a topical treatment using 2% dorzolamide in three patients. The methods performed were OCT scan with a Spectralis HRA-OCT, for the measurement of macular thickness and morphology; best corrected visual acuity was assessed using Early Treatment Diabetic Retinopathy Study (ETDRS), was assessed slit-lamp biomicroscopy, ocular tonometry, fundus biomiocrosopy, and color fundus photography. This therapeutic protocol has been applied and described in three patients.

RESULTS

In all three tested patients, following the administration of dorzolamide in eye drop, we observed a remarkable decrease in macular edema, almost comparable to that obtained with acetazolamide per os.

CONCLUSION

The study confirms the anti-edematogenic effect of topical dorzolamide in RP with recurring macular cysts, as this can have a favorable response with topical dorzolamide. In all the three examined patients, the instillation of topical dorzolamide caused a remarkable reduction in their macular edema, as highlighted on OCT.

Immunosuppressive Treatment for Retinal Degeneration in Juvenile Neuronal Ceroid Lipofuscinosis (Juvenile Batten Disease)

Juvenile Neuronal Ceroid Lipofuscinosis (JNCL) presents with progressive vision loss at 4-7 years of age. Blindness results within 2 years, followed by inexorable neurologic decline and death. There is no treatment or cure. Neuroinflammation is postulated to play a role in the neurodegeneration. The JNCL mouse model demonstrated decreased neuroinflammation and improved motor skills with immunosuppression. Based on this work, a short-term human clinical trial of mycophenolate mofetil has begun, however longer term effects, and whether immunosuppression modulates vision loss, have not been studied. We report a JNCL patient treated with immunosuppressive therapy in whom visual function was comprehensively characterized over 2 years.

The prevalence of macular cysts in patients with clinical cone-rod dystrophy determined by spectral-domain optical coherence tomography

BACKGROUND

To determine the prevalence of macular cysts in patients with clinical cone-rod dystrophy (CORD) using spectral-domain optical coherence tomography (SD-OCT). If macular cysts could be demonstrated in such patients, they might benefit from treatment with a carbonic anhydrase inhibitor that has been shown to be effective for treating macular cysts in various night-blinding disorders.

MATERIAL AND METHODS

Thirty-six CORD patients underwent a complete ophthalmic examination and an SD-OCT examination using two different systems. The presence of hypo-reflective lacunae was used to determine the presence of macular cysts.

RESULTS

The patients' mean age was 42.9 ± 19.5 years (range 6-71 years). Mean BCVA was 1.09 ± 0.64 logMAR (range no light perception to 20/25 + 2 in the better-seeing eye). All the 72 eyes studied showed a variable degree of retinal thinning, disruption of what has been referred to as the inner segment ellipsoid and outer nuclear layer (ONL) thinning of the macula. None showed evidence of macular cysts on OCT testing.

CONCLUSIONS

Although macular cysts are a common feature of various hereditary night-blinding retinal dystrophies, these were not identified in our cohort of CORD patients.

Unilateral retinitis pigmentosa: a proposal of genetic pathogenic mechanisms

PURPOSE

To investigate and integrate anatomic and physiologic findings from a group of patients who present retinitis pigmentosa affecting just one eye and use this information to propose mechanisms of disease pathogenesis.

METHODS

This prospective cross-sectional study examined 5 patients, all female, from 8 to 60 years old. The study was conducted in 4 university hospitals. The patients were selected according to the characteristics of ocular involvement, notably unilateral presentation of similar anatomic and functional abnormalities. Full-field electroretinogram, fundus photography, fundus autofluorescence, infrared imaging, optical coherence tomography, and genetic testing were performed.

RESULTS

Full-field electroretinogram showed unilateral decrease in amplitude and increase in implicit time; autofluorescence showed unilateral areas of decreased intensity. The USH2AW4149R mutation was confirmed in one patient.

CONCLUSIONS

Imaging and functional testing are important in elucidating the unilateral pattern of the disease and in monitoring these individuals. Mosaicism or somatic mutation may cause unilateral genetic disease presentation.

Therapeutic challenges to retinitis pigmentosa: from neuroprotection to gene therapy

Syndromic retinitis pigmentosa (RP) is the result of several mutations expressed in rod photoreceptors, over 40 of which have so far been identified. Enormous efforts are being made to relate the advances in unraveling the patho-physiological mechanisms to therapeutic approaches in animal models, and eventually in clinical trials on humans. This review summarizes briefly the current clinical management of RP and focuses on the new exciting treatment possibilities. To date, there is no approved therapy able to stop the evolution of RP or restore vision. The current management includes an attempt at slowing down the degenerative process by vitamin supplementation, trying to treat ocular complications and to provide psychological support to blind patients. Novel therapeutic may be tailored dependant on the stage of the disease and can be divided in three groups. In the early stages, when there are surviving photoreceptors, the first approach would be to try to halt the degeneration by correction of the underlying biochemical abnormality in the visual cycle using gene therapy or pharmacological treatment. A second approach aims to cope with photoreceptor cell death using neurotrophic growth factors or anti-apoptotic factors, reducing the production of retino-toxic molecules, and limiting oxidative damage. In advanced stages, when there are few or no functional photoreceptors, strategies that may benefit include retinal transplantation, electronic retinal implants or a newly described optogenetic technique using a light-activated channel to genetically resensitize remnant cone-photoreceptor cells.

Clinical and Rehabilitative Management of Retinitis Pigmentosa: Up-to-Date

The term retinitis pigmentosa (RP) indicates a heterogeneous group of genetic rare ocular diseases in which either rods or cones are prevalently damaged. RP represents the most common hereditary cause of blindness in people from 20 to 60 years old. In general, the different RP forms consist of progressive photo-receptorial neuro-degenerations, which are characterized by variable visual disabilities and considerable socio-sanitary burden. Sometimes, RP patients do not become visually impaired or legally blind until their 40-50 years of age and/or maintain a quite acceptable sight for all their life. Other individuals with RP become completely blind very early or in middle childhood. Although there is no treatment that can effectively cure RP, in some case-series the disease's progression seems to be reducible by specific preventive approaches. In the most part of RP patients, the quality of vision can be considerably increased by means of nanometer-controlled filters. In the present review, the main aspects of the routine clinical and rehabilitative managements for RP patients are described, particularly focusing on the importance of specific referral Centers to practice a real multidisciplinary governance of these dramatic diseases.