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Clinical Trial
, 32 (5), 996-1006

Treatment of Nonneovascular Idiopathic Macular Telangiectasia Type 2 With Intravitreal Ranibizumab: Results of a Phase II Clinical Trial

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Clinical Trial

Treatment of Nonneovascular Idiopathic Macular Telangiectasia Type 2 With Intravitreal Ranibizumab: Results of a Phase II Clinical Trial

Brian C Toy et al. Retina.

Abstract

Purpose: To evaluate the safety and preliminary efficacy of intravitreal ranibizumab for nonneovascular idiopathic macular telangiectasia Type 2.

Methods: Single-center, open-label Phase II clinical trial enrolling five participants with bilateral nonneovascular idiopathic macular telangiectasia Type 2. Intravitreal ranibizumab (0.5 mg) was administered every 4 weeks in the study eye for 12 months with the contralateral eye observed. Outcome measures included changes in best-corrected visual acuity, area of late-phase leakage on fluorescein angiography, and retinal thickness on optical coherence tomography.

Results: The study treatment was well tolerated and associated with few adverse events. Change in best-corrected visual acuity at 12 months was not significantly different between treated study eyes (0.0 ± 7.5 letters) and control fellow eyes (+2.2 ± 1.9 letters). However, decreases in the area of late-phase fluorescein angiography leakage (-33 ± 20% for study eyes, +1 ± 8% for fellow eyes) and in optical coherence tomography central subfield retinal thickness (-11.7 ± 7.0% for study eyes and -2.9 ± 3.5% for fellow eyes) were greater in study eyes compared with fellow eyes.

Conclusion: Despite significant anatomical responses to treatment, functional improvement in visual acuity was not detected. Intravitreal ranibizumab administered monthly over a time course of 12 months is unlikely to provide a general and significant benefit to patients with nonneovascular idiopathic macular telangiectasia Type 2.

Figures

Figure 1
Figure 1. Effect of intravitreal ranibizumab on visual acuity in participants with IMT2
(A) Summary of visual acuity change from baseline at all study visits for each study participant. Each histogram column shows the change in visual acuity score (in ETDRS letters) from baseline for all study visits (visits 1 through 14) arranged in order. Changes for the study eye (top) and untreated fellow eye (bottom) are shown. (B) Mean change in visual acuity score from baseline over time for study eyes (n=5) and fellow eyes (n=5). The error bars represent standard deviation. No statistical difference was observed between study eyes and fellow eyes at any time point (p>0.05 for all comparisons, paired t-test).
Figure 2
Figure 2. Effect of intravitreal ranibizumab on late-phase leakage on fluorescein angiography (FA) in participants with IMT2
(A) Summary of change in the area of late-phase leakage on FA from baseline for each study participant. Each histogram column shows the percent change in the area of late-phase leakage compared to baseline for the treated study eye (top) and untreated fellow eye (bottom). The response to treatment in all five study eyes was characterized by a prominent decrease in the area of late leakage. Changes from baseline were variable during study follow-up in three out of five fellow eyes (participants #1, #2, and #3) and increased in two out of five fellow eyes (participants #4 and #5). Prior to visit 8 (arrow), participant #5 underwent cataract extraction and intraocular lens implantation in the fellow eye, which demonstrated a post-procedural increase in late-phase leakage that is likely attributable to the effects of surgery (Irvine-Gass syndrome). (B) Mean change in late-phase leakage area from baseline over time, excluding data from participant #5 (n=4, for study and fellow eyes). Significant differences in mean change between study and fellow eyes were apparent following one ranibizumab treatment (p=0.03, paired t-test) and increased to a maximum after four to five treatments. The error bars represent standard deviation.
Figure 3
Figure 3. Clinical effect of intravitreal ranibizumab on vascular leakage and retinal thickness in patients with IMT2
(A) Late-phase phase fluorescein angiographs of participant #2 at baseline (left) and visit #2 (right) in the study (top) and fellow eye (bottom). Eight weeks following the baseline visit and two consecutive intravitreal injections of ranibizumab, the study eye demonstrated a marked reduction in the area of late-phase FA leakage, while the untreated fellow eye showed little interval change. (B) Corresponding optical coherence tomography (OCT) horizontal B-scans traversing the center of the fovea. In the study eye (top), the fovea (arrow) demonstrated reduction in central retinal thickness with a decrease in the size of hyporeflective intraretinal cavities. In the untreated fellow eye (bottom), central retinal thickness remained relatively stable.
Figure 4
Figure 4. Effect of intravitreal ranibizumab on retinal thickness as measured by optical coherence tomography (OCT) in participants with IMT2
(A) Summary of change in the central subfield retinal thickness on OCT from baseline for each study participant. Each histogram column shows the percent change from baseline in retinal thickness measured in the central (1mm diameter) subfield in the treated study eye (top) and untreated fellow eye (bottom). The response to treatment in all five study eyes was characterized by a predominant decrease in central subfield thickness. In fellow eyes, changes from baseline were smaller and more variable in four out of five fellow eyes (participants #1, #2, #3, and #4). Participant #5 underwent cataract extraction in the fellow eye prior to visit 8 (arrow), which demonstrated a post-procedural increase in OCT thickness that is likely attributable to the effects of surgery (Irvine-Gass syndrome). (B) Mean change in central subfield retinal thickness from baseline over time, excluding data from participant #5 (n=4, for study and fellow eyes). Significant differences in mean change between study and fellow eyes were apparent following one ranibizumab treatment (p=0.03, paired t-test) and maintained thereafter. (C–F) Similar trends in retinal thickness were also observed in all four paracentral quadrants adjoining the central retinal subfield. Mean decreases in retinal thickness in treated eyes were greatest in the temporal paracentral quadrant compared to the other (nasal, superior, and inferior) paracentral quadrants. The error bars represent standard error of the mean. Asterisks indicate significant differences between study and fellow eyes (paired t-test, n =4).
Figure 5
Figure 5. Effect of intravitreal ranibizumab on retinal sensitivity as measured by microperimetry in participants with IMT2
Microperimetric measurements were performed using the Nidek MP-1 microperimeter. A 68-loci circular grid centered on the macula and covering the central 20° was employed. (A) The ability of the participant to respond to stimulus light projected at particular retinal loci was evaluated, and retinal sensitivity at each loci was measured on a scale from 0 (low sensitivity) to 20 dB (high sensitivity). (B) A subset of testing points was also identified as being located within the retinal area involving late-phase fluorescein leakage by overlaying the MP1 test grid upon a late-phase image of the fluoroscein angiograph (left). In this way, two sets of points were identified for analysis: (1) all 68 points in the testing grid, and (2) a subset of points in the testing grid found within the area of the retina involving late-phase FA leakage (points highlighted in red, right). Summaries of the mean change in retinal sensitivity from baseline at visits 3, 9, and 13 are shown for each study patient for (D) all points and (E) points in the area of leakage only. Each histogram column shows the mean change in retinal sensitivity compared to baseline visit for the treated study eye (top) and untreated fellow eye (bottom). By the end of follow-up, three study eyes exhibited a net increase in retinal sensitivity (participants #2, #3, and #4), compared to none of the fellow eyes. Participant #5 underwent cataract extraction in the fellow eye prior to visit 8 (arrow). (F–G) Mean change in mean retinal sensitivity from baseline was calculated for all testing points (F) and for points involving FA leakage only (G), excluding data from participant #5 (n=4, for study and fellow eyes).

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