Clinical Features Of The Congenital Hypertrophy Of The Retinal Pigment Epithelium

[Objective] In order to investigate the clinical features of the fundus photography and fluorescein angiography and optical coherence tomography in congenital hypertrophy of the retinal pigment epithelium(CHRPE)in patients with a diagnosis of familial adenomatous polyposis.[Method] Prospective the fundus photography and fluorescein angiography and optical coherence tomography were carried out in 66 patients(132eyes)from Changhai hospital with 234 CHPRE lesions.The main outcome measures included flat lesion enlargement,intralesional lacunae enlargement,and development of an elevated nodule within the lesion,retinal and retinal pigment epithelium(RPE)thickness relative to normal tissue and the status of the retinal layers,in particular the photoreceptor layer.The clinical features at the time of presentation were analyzed for their impact on the main outcomes using a series of Cox proportional hazards regressions.[Results] The median largest basal diameter was 4.5mm.Lacunae were noted in 43% of the pigmented CHRPE.Flat enlargement of the lesion was documented in 46% of patients with comparative photographic follow-up and in 83% of those followed up for more than 3 years.The median rate of enlargement was 10μm per month.About 73.8% of CHRPE lesions were close to retinal vessels.The retinal vascular changes were: capillary non-perfusion with an area(46.2%),attenuation of retinal vessels(7.7%),chorioretinal anastomoses(6.2%),capillary microaneurysms(3.1%),choriocapillary vessels observed(4.6%)and in the depigmented marginal halo(20%).About 10% of the lesions were not seen on ophthalmoscopy and could only be detected by angiography.All patients showed retinal thinning and complete photoreceptor loss overlying the CHRPE.The sensory retina measured a mean of 68% of normal thickness.Of the 52 patients with pigmented CHRPE,the CHRPE was 52% thicker than adjacent RPE.All 52 patients with pigmented CHRPE showed moderate relative shadowing of the underlying choroid.The 14 patients with nonpigmented CHRPE,presumed to represent large lacunae with thin CHRPE rim,showed absent RPE and increased transmission of light,not shadowing,into the choroid by OCT.[Conclusion] Congenital hypertrophy of the retinal pigment epithelium has not been regarded as a stable lesion.The most important factor associated with flat lesion enlargement was relative size of the lacunae within CHRPE.Factors related to lacunae enlargement included number and relative size of lacunae.Even though the diagnosis of CHRPE is clinical,fluorescein angiography may be useful in confirming the diagnosis,as well as detecting additional lesions not seen by means of ophthalmoscopic examination.Using OCT,overlying retinal thinning and photoreceptor loss directly over CHRPE was found in all patients.Other findings of importance by OCT included mild retinal thinning overlying the CHRPE in all 66 patients,likely the result of the photoreceptor absence.If this were confirmed,then ocular examination should be performed regularly in subjects who do not show any lesion but who have been identified as being at risk.