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Development and Validation of a Commercially Available Two Color Dark Adapted Perimetry to Assess Inherited Retinal
Mark E Pennesi1, Alessia Amato2, Wayne Tschetter3
1From the Retina Foundation of the Southwest (M.E.P., D.G.B.), Dallas, Texas, USA; Casey Eye Institute (M.E.P., W.T., R.S., A.D.I., L.A.E., P.Y., S.J.H.), Oregon Health & Science University, Portland, Oregon, USA.
A new 2-color dark-adapted perimetry (2cDAP) protocol effectively assesses rod and cone function in inherited retinal degenerations (IRDs). This method is repeatable and sensitive to early rod function loss, aiding clinical trials for retinitis pigmentosa (RP).
Area of Science:
- Ophthalmology
- Neuroscience
- Medical Imaging
Background:
- Inherited retinal degenerations (IRDs), such as retinitis pigmentosa (RP), cause progressive vision loss due to photoreceptor dysfunction.
- Accurate assessment of rod and cone function is crucial for monitoring disease progression and evaluating treatment efficacy in IRDs.
- Current perimetry methods may not adequately capture early or specific photoreceptor deficits, particularly rod dysfunction.
Purpose of the Study:
- To develop and validate a commercially available 2-color dark-adapted full field perimetry (2cDAP) protocol.
- To assess rod and cone function in patients with inherited retinal degenerations (IRDs), specifically retinitis pigmentosa (RP).
- To establish a reproducible method for measuring rod function to aid in evaluating treatment efficacy in clinical trials.
Main Methods:
- Developed a 2cDAP protocol using the Octopus 900 Pro perimeter with blue (450 nm) and red (610 nm) stimuli under dark-adapted conditions.
- Calculated spectral sensitivity difference (SSD) to differentiate rod and cone function.
- Tested 35 RP patients and 14 controls using 2cDAP and standard light-adapted perimetry (LAP); collected 12-month longitudinal data from 12 RP patients.
Main Results:
- 2cDAP showed high repeatability in controls and consistency across institutions, with testing times comparable to LAP.
- The protocol detected rod-mediated function in areas missed by LAP.
- Longitudinal data revealed faster progression in rod-mediated function compared to cone-mediated function, highlighting 2cDAP's sensitivity to early rod loss.
Conclusions:
- The 2cDAP protocol offers a robust, spatially resolved assessment of photoreceptor function in IRDs.
- Its ability to differentiate rod and cone contributions and its availability on commercial equipment make it suitable for multicenter clinical trials.
- Future research will focus on protocol refinement, expanding normative data, and validation in larger cohorts.
