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. 2015:2015:247259.
doi: 10.1155/2015/247259. Epub 2015 Oct 7.

A Comparative Study of Retinal Function in Rabbits after Panretinal Selective Retina Therapy versus Conventional Panretinal Photocoagulation

Young Gun Park  1 , Seungbum Kang  1 , Ralf Brinkmann  2 , Young-Jung Roh  1
Affiliations

A Comparative Study of Retinal Function in Rabbits after Panretinal Selective Retina Therapy versus Conventional Panretinal Photocoagulation

Young Gun Park et al. J Ophthalmol. 2015.

Abstract

Purpose. This study evaluates functional changes in electroretinographic findings after selective retina therapy (SRT) compared to panretinal photocoagulation (PRP) in rabbits. Methods. The right eyes of 12 Chinchilla rabbits received 200 laser treatment spots. The right eyes of six rabbits received SRT (SRT group), whereas the other six animals were treated using PRP on the right eye (PRP group). The eyes were investigated using full-field ERG 1 hour and 3 weeks after treatment. Histologic exam to assess the tissue response of lasers was performed on 3 weeks. Results. No significant changes in the mean ROD or CR b-wave amplitudes of the SRT lesions were evident, compared to baseline, 1 h after laser treatment (p = 0.372 and 0.278, resp.). In addition, the OPs and 30 Hz flickers of the SRT lesions were not significantly altered (p = 0.17 and 0.243, resp.). At 3 weeks, similar results were found. Comparing the two groups, the ROD b-wave amplitude was reduced in the PRP and SRT groups to 60.04 ± 4.2% and 92.32 ± 6.43% of baseline (p < 0.001). Histologically, there was no visible photoreceptor alterations on week 3. Conclusions. SRT in rabbit eyes induced less functional loss than PRP in both rod-mediated retinal function and cone-mediated retinal function. In addition, SRT irradiated eyes had no functional loss compared to its control.

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Figures

Figure 1
Figure 1
Schematic sketch of the reflectometry. The system contained two photodiodes; one of them (P1) detects the laser pulses applied to the fundus, and the other (P2) detects reflected and backscattered light from the retina. As a result, reflectometry can stop laser irradiation appropriately for selective RPE damage.
Figure 2
Figure 2
(a) A fundus image obtained 1 h after selective retina therapy (SRT) revealed no visible SRT spots. (b) Fluorescein angiography (FA) performed 1 hr after the irradiation showed hyperfluorescence on SRT spots. (c) A fundus photograph taken 1 hr after conventional PRP showed whitish spots. (d) FA performed 1 hr after PRP showed larger hyperfluorescence than that of SRT, although the same spot size (200 μm) was applied.
Figure 3
Figure 3
Dark-adapted ERG in the control group (top). ERG responses in the SRT groups were not significantly different from those of the control groups at either 1 h or 3 weeks after irradiation. (a, b, middle) However, the amplitudes of the conventional PRP group were significantly lower at these two time points (a, b, bottom).
Figure 4
Figure 4
None of the b-wave amplitudes of the rods, CR, the amplitudes of the oscillatory potentials, or the 30-Hz flicker of the SRT group was significantly decreased. However, those of the conventional PRP group were significantly less than the control group.
Figure 5
Figure 5
(a, b) The photoreceptor inner segments were preserved, and the distal ends of the photoreceptor outer segments were slightly relaxed. The RPE layer proliferated focally along the SRT lesion, and Bruch's membrane was intact. Histology of conventional laser lesions after 3 weeks. (c, d) The full-thickness structure of the retina involving the photoreceptors was disrupted and disorganized (magnification 200x; a, c) (magnification 400x; b, d) (red arrow, irradiated lesion).
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