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Patching helps improve macular function in patients with central serous retinopathy
Some patients suffering from central serous retinopathy experienced improvement in multifocal ERG after 24 hours of treatment.
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An ongoing study investigating the efficacy of patching has shown some promising results in patients with central serous retinopathy.
Specifically, the study is evaluating whether 24-hour patching is a feasible and effective treatment modality for central serous retinopathy (CSR). Earl and colleagues are also looking to identify a physiological explanation for the disease, “namely if inhibition of photic stimulation of the diseased retina will aid in ameliorating disease severity and disease duration,” according to the study.
The interventional, nonrandomized efficacy study is being conducted by researchers at the Washington University School of Medicine.
At Retina 2014 in January, Rajendra Apte, MD, PhD, a sub-investigator for the study, provided more insight as well as an update on its progress. Apte noted that, at that point, the study had evaluated eight participants.
“CSR is, by definition, a localized serous detachment of the neurosensory retina from the retinal pigment epithelium (RPE) in the region of the very metabolically active macula,” he noted in his presentation. “By limiting the light-induced stress on the macula with patching, there may be a resultant decrease in the long-term loss of visual function associated with an active visual cycle.”
Study design
Apte explained that participants are eligible if they have CSR of any duration and have received no prior treatment. At baseline, participants undergo an examination that includes visual acuity, Optomap imaging (Optos, Marlborough, Mass.), optical coherence tomography and multifocal electroretinography (mfERG).
Participants are then patched overnight until they are seen the next day, when the examination and tests are repeated.
“Essentially, it blocks the light photons from entry into the eye, and then the first time they would see light after 24 hours would be when they have the ERG,” Apte said.
“Visual cycle modulators suppress the phototoxic stress placed on cells involved in the visual cycle by inhibiting key visual cycle enzymes to avoid the accumulation of cytotoxic compounds,” Apte and his colleagues wrote in their paper, which was published online in Ophthalmology.
Preliminary results showed that four participants experienced improvement in their mfERG after patching for 24 hours. Additionally, one participant showed modest improvement in OCT mean central thickness, and two showed mild improvement in visual acuity. Overall, seven of eight patients showed an improvement in at least one parameter.
“But this means that for four patients out of eight there was no improvement in mfERG,” Apte noted. “So it’s about 50% so far.”
As detailed in their paper, the researchers also patched and examined five normal controls. They found no significant difference in mfERG in these participants.
Apte discussed the results of one participant in detail, noting the patient had a large neurosensory detachment that involved a substantial area of the macula.
“There are recordings of the multifocal ERG, at least in the foveal center, where you can get some recovery of visual function, really making it an exciting potential avenue for research in terms of improving macular function,” he said.
“These results provide evidence that, in some cases, short-term suppression of the visual cycle via patching results in improved visual function as assessed by mfERG in patients with CSC,” the authors wrote in Ophthalmology.
They said that the lack of resolution or improvement of subretinal fluid on OCT indicates that the improvement seen in mfERG is not due to anatomic changes, but may be due to functional improvement resulting from visual cycle suppression.
The researchers stated that they were still unsure as to why only some patients showed improvement.
“Potential explanations include lack of compliance or incomplete patching in some patients or a differing effect owing to chronicity of CSC or prior episodes of CSC that may have resulted in a greater degree of accumulated damage that was beyond the scope of this therapeutic intervention,” they said. “It is possible that, with a larger study population, subgroups may be identified that show differing responses to visual cycle suppression via patching. Further studies are needed to determine which CSC patients are most likely to benefit from visual cycle suppression, and whether other pharmacologic forms of visual cycle suppression may be useful in the treatment of CSC.”
In closing his presentation, Apte acknowledged additional questions that the researchers are investigating, including whether the degree of variation of mfERG results is significant, as well as the goal of the study.
“Possibly up to 50% of patients have improvement in multifocal ERG responses, but their underlying condition is still persistent because they still have leakage and neurosensory retinal detachment,” he said. “So how is this really going to translate into treatment?” he asked.
“I’m not proposing that we patch our patients for months to have improvement in visual function,” Apte said. “But the goal would be to use many of these visual cycle inhibitors and see whether, in these hard-to-treat patients, we can at least maintain macular and cone function until either the condition resolves, the patient stops steroids or you try other modalities such as photodynamic therapy or anti-VEGFs and allow the retina to heal while the patient is recovering from their neurosensory detachment. Prospective trials will be useful in determining the efficacy and safety of visual cycle inhibitors in CSR.”
Applications for optometry
Jerome Sherman, OD, FAAO, a distinguished teaching professor in the Clinical Optometric Science Department at SUNY College of Optometry and Primary Care Optometry News Editorial Board member, spoke with PCON about how the results translate to clinical applications for optometrists.
Sherman noted that while the study was small, the results thus far were interesting.
“This is certainly an intriguing preliminary study that should be expanded to large numbers of patients with perhaps some other conditions included,” he said. “However, it seems to show something that would surprise most of us.”
In terms of its application, Sherman explained that the technique would be straightforward to incorporate into practice and recommended that optometrists consider it in some cases.
Jerome
Sherman
“The procedure, presumably, is safe,” he stated. “Optometrists and ophthalmologists are allowed to patch. We patch for other conditions all the time, so it’s certainly within the standard of care to try this approach. So if you have a patient with central serous retinopathy and you’re trying to figure out what to do next, I think attempting a 24-hour period of patching would certainly be a worthwhile approach.”
Sherman said optometrists may want to try this in select cases for a short period of time to see if symptoms improve, visual acuity changes, central fields change on a 10-2 visual field or the mfERG or pattern ERG demonstrate change.
“Autofluorescence, especially ultra-widefield autofluorescence, would be helpful in order to image the RPE,” he added. “Because the RPE is implicated in CSR and is where much of the disease process is taking place, RPE changes are also highly correlated with the photoreceptors.”
Sherman also contrasted the use of patching with the use of a visual cycle inhibiting drug.
“To my knowledge, there are no visual cycle inhibitors that are approved by the U.S. Food and Drug Administration at the present time, but this study suggests that if patching can work, then maybe a drug that can alter the visual cycle is worth exploring,” he said. – by Chelsea Frajerman