The pattern electroretinogram (PERG) after laser treatment of the peripheral or central retina

Structural and Functional Characteristics of Color Vision Changes in Choroideremia

Color vision is considered a marker of cone function and its assessment in patients with retinal pathology is complementary to the assessments of spatial vision [best-corrected visual acuity (BCVA)] and contrast detection (perimetry). Rod-cone and chorioretinal dystrophies—such as choroideremia—typically cause alterations to color vision, making its assessment a potential outcome measure in clinical trials. However, clinical evaluation of color vision may be compromised by pathological changes to spatial vision and the visual field. The low vision Cambridge Color Test (lvCCT) was developed specifically to address these latter issues. We used the trivector version of the lvCCT to quantify color discrimination in a cohort of 53 patients with choroideremia. This test enables rapid and precise characterization of color discrimination along protan, deutan, and tritan axes more reliably than the historically preferred test for clinical trials, namely the Farnsworth Munsell 100 Hue test. The lvCCT demonstrates that color vision defects—particularly along the tritan axis—are seen early in choroideremia, and that this occurs independent of changes in visual acuity, pattern electroretinography and ellipsoid zone area on optical coherence tomography (OCT). We argue that the selective loss of tritan color discrimination can be explained by our current understanding of the machinery of color vision and the pathophysiology of choroideremia.

Giant Cell Tumor of the Uterus: A Report of 3 Cases With a Spectrum of Morphologic Features

Giant cell tumors, a well-recognized neoplasm of bone, can rarely be found in the uterus. Such tumors are characterized by a dual population of mononuclear and osteoclast-like giant cells that lack epithelial and specific mesenchymal differentiation. In this study, the clinicopathologic features of 3 giant cell tumors of the uterus were reviewed. Immunohistochemistry for CD68, CD163, h-caldesmon, desmin, SMA, AE1/AE3, CD10, ER, PR, cyclin D1, CD1a, CD34, CD30, S100, myogenin/myoglobin, and Ki-67 was performed in all tumors, along with ultrastructural analysis in one. The patients were 47, 57, and 59 yr and the tumors measured 2.5, 7.5, and 16.0 cm. One neoplasm was confined to the endometrium, whereas the other 2 were myometrial. All 3 tumors showed a nodular growth comprised of mononuclear and osteoclast-like giant cells. The endometrial-confined tumor consisted of histologically benign mononuclear cells, whereas the others exhibited marked atypia. Mitotic activity was up to 5/10 HPF in the benign tumor and up to 22/10 HPF in the malignant. No cytologic atypia or mitoses were observed in the giant cells. CD68 and CD10 were strongly and diffusely expressed in both components of 3 and 2 neoplasms, respectively. Cyclin D1 was focal in the mononuclear cells and focal to diffuse in the giant cells. CD163 was diffuse in the mononuclear cells, but absent to focal in the giant cells. Ultrastructural analysis lacked diagnostic features of epithelial or specific mesenchymal differentiation. Both malignant tumors demonstrated an aggressive behavior. In summary, although rare, giant cell tumor of the uterus should be included in the differential diagnosis of benign or malignant tumors containing osteoclast-like giant cells.

A randomized trial to assess functional and structural effects of ranibizumab versus laser in diabetic macular edema (the LUCIDATE study)

PURPOSE

To compare the functional and structural effects of ranibizumab versus macular laser therapy in patients with center-involving diabetic macular edema.

DESIGN

Prospective, randomized, single-masked clinical trial.

METHODS

SETTING

Single center.

STUDY POPULATION

Thirty-three eyes of 33 patients with center-involving diabetic macular edema, with best corrected visual acuity of 55 to 79 Early Treatment Diabetic Retinopathy Study letters at baseline, completing the 48-week study period.

INTERVENTION

Subjects were randomized 2:1 to 3 loading doses of ranibizumab then retreatment every 4 weeks as required; or macular laser therapy at baseline, repeated as required every 12 weeks. Exploratory Outcome Measures: Structural imaging studies included greatest linear dimension and area of foveal avascular zone, perifoveal capillary dropout grade, and presence of morphologic features of diabetic macular edema on Spectralis optical coherence tomography (Heidelberg Engineering GmbH, Heidelberg, Germany). Functional measures: Visual acuity, retinal sensitivity in the central 4 and 12 degrees on microperimetry, color contrast sensitivity protan and tritan thresholds, pattern and full-field electroretinogram amplitudes and implicit times, and multifocal electroretinogram amplitude distribution. These were reported at 12, 24, and 48 weeks.

RESULTS

Ranibizumab-treated subjects gained 6.0 vs 0.9 letters lost for laser, demonstrated improved tritan and protan color contrast thresholds, and improved retinal sensitivity. Electrophysiologic function also improved after ranibizumab therapy. No safety issues were evident. Better retinal thickness reduction and structural improvement in optical coherence tomography features of diabetic macular edema were seen with ranibizumab therapy than in the laser group. There was no evidence of progressive ischemia with ranibizumab therapy.

CONCLUSIONS

Ranibizumab therapy in the treatment of diabetic macular edema seems to improve retinal function and structure as demonstrated by this evaluation of different assessment methods.

Ocular manipulation reduces both ipsilateral and contralateral electroretinograms

PURPOSE

To determine the electroretinogram (ERG) changes in eyes manipulated in the course of local ablative therapy (transpupil thermotherapy (TTT), cryotherapy or both) or scleral depression and in un-manipulated fellow, healthy eyes.

METHODS

This prospective observational report summarizes 73 ERG studies in 42 patients with retinoblastoma; a study consisted of ERGs of one or both eyes (if present) followed by ocular manipulation (scleral depression, cryotherapy, transpupillary thermotherapy, pressure applied to orbital implant in an anophthalmic socket, or a 5- or 10-min delay without mechanical manipulation) followed by a repeat of the ERGs. Each patient was studied with only a single manipulation modality on any given date: 23 patients were studied only once, and 19 patients were included in more than one study occasion.

RESULTS

Following local ablative treatment of patients with unilateral retinoblastoma, the photopic response decreased significantly in both the treated eye and the untouched fellow, healthy eye. Following scleral depression of the diseased eye, the photopic response immediately decreased in the diseased eye by a mean of 16 μV (21 %, p = .006) and, in the fellow, healthy eye by 40 μV (23 %, p = .0005). Following scleral depression of the fellow, healthy eye, the photopic response immediately decreased by a mean of 11 μV (4 %, p = .37) in the fellow, healthy eye, and by 16 μV (28 %, p = .01) in the diseased eye.

CONCLUSIONS

Following physical ocular manipulation, the amplitude of the photopic response decreased in the manipulated, but also the untouched healthy, fellow eyes. These findings may account for some of the variation in clinical ERG recordings, particularly that observed following ocular manipulation by TTT, laser or even scleral depression.

Retinal function and PKC alpha expression after focal laser photocoagulation

PURPOSE

To examine the effects of focal laser photocoagulation on general and local retinal function and to relate electrophysiological findings with changes in protein kinase C (PKC) alpha expression.

METHODS

Twelve rabbits were treated with 70 spots of laser photocoagulation in the central cone-rich retina. The operated eyes were investigated with electroretinography (full-field ERG and multifocal electroretinography, mfERG) preoperatively and at 1, 3, and 5 weeks after surgery. The expression of PKC alpha was examined at all three time points using immunohistochemistry, and PKC alpha mRNA levels were quantified using real-time polymerase chain reaction (PCR). Immunohistochemistry for glial fibrillary acidic protein (GFAP) and hematoxylin and eosin staining was employed to monitor the extent and dynamics of the morphological response.

RESULTS

The full-field ERG revealed a significant increase in b-wave amplitudes derived from the isolated rod response (blue light) at all three time points after surgery (p < 0.05). Supernormal b-wave amplitudes were also found for the combined rod-cone response at 3 weeks (white light), and for the isolated cone response (light-adapted 30-Hz flicker) at 5 weeks after treatment. In the mfERG, amplitudes derived from the central retina did not change postoperatively, while the implicit time was significantly increased at all time points. Immunohistochemistry for PKC alpha revealed a reduced expression of the enzyme in rod bipolar cells 1 and 3 weeks after laser treatment compared with untreated controls. Five weeks postoperatively, no PKC alpha labeling in rod bipolar cells was found in any part of the retina. Real-time PCR 1 and 3 weeks after treatment displayed a decreased level of PKC alpha mRNA compared to the controls. Immunolabeled tissue sections from laser-treated eyes displayed GFAP expression in Müller cells in the treated as well as untreated retina 1 week postoperatively. At 3 and 5 weeks, GFAP labeling was less pronounced and was concentrated around the laser-treated spots.

CONCLUSIONS

Focal laser treatment in the rabbit eye induces local and wide-spread alterations in both rod- and cone-mediated retinal function in the form of supernormal b-wave amplitudes in the full-field ERG and increased latency in the mfERG. The electrophysiological abnormalities are accompanied by a progressive down-regulation of the PKC alpha isoenzyme in rod bipolar cells, reaching far beyond the treated area. PKC alpha is down-regulated directly by impaired protein synthesis, and also possibly indirectly by protein consumption related to GFAP up-regulation. The results indicate that focal laser photocoagulation interferes with PKC-alpha-mediated inhibitory regulation of inner retinal signal transmission.