The Lack of Concordance Between Subretinal Drusenoid Deposits and Large Choroidal Blood Vessels

Abstract

 

Purpose

 

To evaluate the concordance between pseudodrusen as manifested by subretinal drusenoid deposits (SDD) and large choroidal blood vessels using stereologic analysis of spectral domain optical coherence tomography (SD-OCT) images.

 

Methods

 

Thirty-one OCT images of 31 subjects with the clinical appearance of pseudodrusen were retrospectively reviewed. A grid of 19 evenly spaced vertical lines was randomly superimposed on each SD-OCT image using ImageJ to perform uniform random systematic sampling. Two independent readers graded the number of times a line crossed a SDD only, a large choroidal vessel only, both or neither. If SDD and large choroidal vessels were independent, the probability of sampling both should lie within the 95% confidence interval, as calculated using the binomial theorem, of the product of the probabilities of crossing SDD and those crossing a large choroidal vessel.

 

Results

 

The mean ± standard deviation age of 31 subjects was 82.9 ± 7.0 years. A total of 589 lines were analyzed. The number of events of the sampling lines intersecting SDD only, large choroidal vessels only, both and neither were 51 (8.7%), 274 (46.5%), 111 (18.8%) and 153 (26.0%), respectively. The probability of the lines crossing both SDD and large choroidal vessels was 0.19 while the probabilities of the lines crossing SDD only and large choroidal vessels only were 0.28 and 0.65, respectively (0.28 X 0.65 ≈ 0.19). This result was within the 95% CI of 0.15-0.21, signifying the SDD were neither associated with large choroidal vessels nor the intervals in between.

 

Conclusions

 

This is the first study to use stereologic techniques to obtain an unbiased estimate of the potential concordance between SDD and large choroidal vessels. Our results demonstrate that there is no concordance between SDD and large choroidal vessels. As a consequence, hypotheses postulating that SDD are associated with large choroidal vessels or the choroidal stromal spaces between the vessels should be abandoned.

 

 

Seventy-five years old AMD patient with pseudodrusen. A. Multiple conventional drusen are shown in color fundus photography with an area of pseudodrusen in the superior macula. B. Pseudodrusen are clearly seen on IR image, with some having a target appearance. C. SD-OCT image with superimposed random uniform 19-vertical line grid using ImageJ.

 

Keywords: 550 imaging/image analysis: clinical • 504 drusen • 412 age-related macular degeneration