A review of in vivo animal studies in retinal prosthesis research.

BACKGROUND: The development of a functional retinal prosthesis for acquired blindness is a great challenge. Rapid progress in the field over the last 15 years would not have been possible without extensive animal experimentation pertaining to device design and fabrication, biocompatibility, stimulation parameters and functional responses. This paper presents an overview of in vivo animal research related to retinal prosthetics, and aims to summarize the relevant studies. METHODS: A Pubmed search of the English language literature was performed. The key search terms were: retinal implant, retinal prosthesis, artificial vision, rat, rabbit, cat, dog, sheep, pig, minipig. In addition a manual search was performed based on references quoted in the articles retrieved through Pubmed. RESULTS: We identified 50 articles relevant to in vivo animal experimentation directly related to the development of a retinal implant. The highest number of publications related to the cat (n = 18). CONCLUSION: The contribution of animal models to the development of retinal prosthetic devices has been enormous, and has led to human feasibility studies. Grey areas remain regarding long-term tissue-implant interactions, biomaterials, prosthesis design and neural adaptation. Animals will continue to play a key role in this rapidly evolving field.

Comparison of adapted Vryghem macular function test and Lotmar-light interferometer in predicting visual acuity after cataract surgery.

PURPOSE: To assess the accuracy of a newly described macular function test (Vryghem macular function test) adapted to our examination equipment and to compare it to the Lotmar-light interferometer for the preoperative evaluation of cataract patients at the University Eye Clinic, Geneva, Switzerland. METHODS: This prospective study included 71 consecutive patients (72 eyes) who were undergoing uneventful cataract surgery. Testing with the Lotmar-light interferometer and an adapted form of Vryghem macular function test (AVMFT) using a Birkhauser reading chart, a hyperaddition of +8 D and halogen illumination were performed to assess macular function and to predict postoperative visual acuity (VA). The duration of each test and the density and location of lens opacities were also noted. Best-corrected postoperative VA was compared to the predicted values of each test. RESULTS: The positive predictive value was 94.2% for AVMFT compared to 92.2% for the Lotmar-light interferometer. The negative predictive value was 50% for AVMFT compared to 42.9% for the Lotmar-light interferometer. The sensitivity was 83.1% for AVMFT and 79.7% for the Lotmar-light interferometer. The specificity was 76.9% for AVMFT and 69.2% for the Lotmar-light interferometer. The correlation coefficient for AVMFT and preoperative Lotmar results (both in LogMAR) with postoperative best-corrected VA (poBCVA; LogMAR) were similar (0.74 and 0.77 respectively). CONCLUSION: The results of this study suggest that AVMFT is as reliable as the Lotmar-light interferometer in predicting postoperative VA after uneventful cataract surgery. The correlation coefficients with postoperative VA were 0.74 and 0.77, respectively. Both tests showed a high positive (94.2% and 92.2%, respectively) but a low negative (50.0% and 42.9%, respectively) predictive value.