title: Incidence and natural history of proliferative sickle cell retinopathy: observations from a cohort study.
abstract: OBJECTIVE
  To describe the incidence, prevalence, and natural history of proliferative sickle cell retinopathy (PSR).
  
  
  METHODS
  Prospective longitudinal study over 20 years.
  
  
  METHODS
  Newborn screening of 100000 consecutive deliveries from 1973 to 1981 identified 315 children with homozygous sickle cell (SS) disease and 201 with SS-hemoglobin C (SC) disease. By the age of 5 years, 307 SS patients and 166 SC patients were alive and living in Jamaica and were recruited for this ophthalmic study.
  
  
  METHODS
  Description of retinal vascular changes on annual angiography and angioscopy.
  
  
  METHODS
  Incidence and prevalence of PSR and its behavior on follow-up. Progression of PSR was investigated using the number of eyes affected (none, one, both) and the interval until PSR onset.
  
  
  RESULTS
  At last review in January 2000, PSR had developed in 59 patients (14 SS, 45 SC), unilaterally in 36 patients and bilaterally in 23. Incidence increased with age in both genotypes, with crude annual incidence rates of 0.5 cases (95% confidence interval [CI], 0.3-0.8) per 100 SS subjects and 2.5 cases (95% CI, 1.9-3.3) per 100 SC subjects. Prevalence was greater in SC disease, and by the ages of 24 to 26 years, PSR had occurred in 43% subjects with SC disease and in 14% subjects with SS disease. Patients with unilateral PSR had a 16% (11% SS, 17% SC) probability of regressing to no PSR and a 14% (16% SS, 13% SC) probability of progressing to bilateral PSR. Those with bilateral PSR had an 8% (8% SS, 8% SC) probability of regressing to unilateral PSR and a 1% (0 SS, 2% SC) probability of regressing to a PSR-free state. Irretrievable visual loss occurred in only 1 of 82 PSR-affected eyes, and 1 required detachment surgery and recovered normal visual acuity.
  
  
  CONCLUSIONS
  Longitudinal observations over 20 years in a cohort of patients followed from birth confirms a greater incidence and severity of PSR in SC disease, and shows that spontaneous regression occurred in 32% of PSR-affected eyes. Permanent visual loss was uncommon in subjects observed up to the age of 26 years.
authors.affiliation: MRC Laboratories, Kingston, Jamaica.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Downes
authors.forename: Ian R
authors.initials: IR
authors.lastname: Hambleton
authors.forename: Elaine L
authors.initials: EL
authors.lastname: Chuang
authors.forename: Noemi
authors.initials: N
authors.lastname: Lois
authors.forename: Graham R
authors.initials: GR
authors.lastname: Serjeant
authors.forename: Alan C
authors.initials: AC
authors.lastname: Bird
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000755:Anemia, Sickle Cell / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D017546:Angioscopy; D002648:Child; D002675:Child, Preschool; D005260:Female; D005451:Fluorescein Angiography; D006450:Hemoglobin SC Disease / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D006801:Humans; D015994:Incidence; D007563:Jamaica / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D015995:Prevalence; D011446:Prospective Studies; D012164:Retinal Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D012171:Retinal Vessels / Q000473:pathology; D012307:Risk Factors; D017678:Sex Distribution; D014792:Visual Acuity