pigmentary retinopathy

The ocular findings include high myopia, vitreoretinal degeneration, dislocated lenses, cataracts, and retinal detachment.  Some patients have early onset (2-4 years old) night blindness and progress to total blindness before 20 years of age.  Nystagmus, strabismus, small optic discs, glaucoma, and cataracts have been reported.  Poor vision and progressive loss of acuity are common.  The vitreous appears to be condensed into sheets and there may be distortion of the vitreoretinal interface with irregular white dots and lines.  Pigmentary changes are common in the retina which some have described as consistent with choroidal sclerosis and chorioretinal atrophy.  Atrophic changes are often seen in the macula.

Cataracts and a pigmentary retinopathy occur in this condition but only in some, primarily older, patients.  The lens opacities progress and may become visually significant by the third decade.  Bone-spicule-shaped pigment clumping may be present in the midperiphery while the optic disk is often pale and the retinal vessels are attenuated. The ERG responses are consistent with a rod-cone dystrophy.

This is a genetically and clinically heterogeneous condition for which the nosology remains to be worked out.  Not all patients have ocular disease but those who survive infancy may have a pigmentary retinopathy resembling retinitis pigmentosa.  In fact, a 5 year old presented with symptoms of visual loss and night blindness only.  The severeity of the systemic malformations has so far precluded a full description of the ocular phenotype.

Night blindness, the predominant presenting symptom, is often noted in the first decade of life but may not be a significant complaint until the third decade.  Concentric peripheral field loss likewise follows a similar timeline.  ERG responses progressively decrease in amplitude and may become undetectable in the second decade.  The retinal disease progresses relentlessly, albeit slowly, as the result of photoreceptor degeneration and most patients have severe visual handicaps by midlife but there is considerable clinical variation.  The pigmentary retinopathy is typical for classical retinitis pigmentosa with vascular attenuation, perivascular bone-spicule pigment clumping, optic atrophy, and generalized retinal atrophy with relative sparing of the macula early in the disease.  Lens opacities are common in late stages of the disease.

This is a rare type of pigmentary retinopathy with few symptoms in many patients.  Pigment clumps in the form of bone spicules in a paravenous distribution appear as young as 1 year of age and may be present congenitally.  The pigment may begin peripherally and is often segmental but eventually progresses centrally along with chorioretinal atrophy involving the majority of the fundus.  For unknown reasons, males are more severely affected than females.  In one family the retinal changes were associated with hyperopia, esotropia and vitreous degeneration (cells and liquefaction).  There is considerable variation in expressivity among patients and the vision and fundus pigmentation can be highly asymmetrical in the two eyes.  ERG abnormalities likewise vary widely with decreased photopic responses in some individuals and complete lack of both scotopic and photopic responses in severely affected eyes.  Decreased night vision is not a symptom.

This is generally considered to be a stationary condition but long term follow up reveals progression of pigmentary changes, chorioretinal atrophy and increasing constriction of the peripheral visual field.  Symptoms of decreased vision may be noted as early as 3 months of age.  Some patients retain vision of 20/20 or 20/30 into midlife whereas others in the first decade already have count fingers vision.  Likewise the size of the visual field varies widely and is not correlated with age.

Only a few families have been reported.  The macular edema can be traced to retinal capillary leakage throughout the posterior pole as revealed by fluorescein angiography.  Scattered exudates and nerve fiber layer hemorrhages are sometimes seen.  Hyperopia and strabismus are often present as well.  Veils, strands, and white punctate deposits in the vitreous have been described.  Wrinkling of the internal limiting membrane may be present.  The ERG is normal except for elevated rod dark adaptation thresholds.  Light/dark ratios are abnormal on EOG testing and mild dyschromatopsia can be demonstrated.  Patients usually notice problems with their visual acuity in the second decade of life and it can drop to 20/200 at this time with progression to 2/120 - 2/200 in older individuals.  In later stages of the disease a central zone of beaten bronze macular atrophy can be seen.  Surrounding this central atrophy is often an area with pigmentary changes resembling retinitis pigmentosa which can extend into the periphery.

This would seem to be a unique disorder in spite of some similarities to retinitis pigmentosa in which macular cysts are often seen.  The clinical course is distinctly different and the presence of vitreous deposits and hyperopia also can be used as arguments for its separateness.  Molecular DNA evidence showing lack of allelism (Vida infra) is, of course the strongest evidence.

Uniform white dots are symmetrically distributed in the midportion and periphery of the retina but the central portion of the macula is usually relatively spared in early stages of the disease.  These flecks are present in the first decade of life increasing in density and covering larger areas of the retina in older individuals.  Difficulties with night vision are also noted early and visual acuity may be compromised, in the range of 20/40.  By the fifth and sixth decades there may be retinal pigment atrophy in the midperiphery and this eventually progresses to geographic atrophy of the macular RPE as the visual field becomes more constricted.  The fundus in older individuals resembles that seen in retinitis pigmentosa with retinal vascular attenuation, frank bone spicule pigmentation, macular disease, and pallor of the optic nerves with significant loss of vision.  The ERG shows reduction in scotopic responses and mild reductions in photopic amplitudes.

This form of flecked retina is sometimes considered to be a variant of fundus albipunctatus (136880).  In favor of this argument are the observations in families in which some young members have the fundus picture of fundus albipunctatus (136880) while older ones with more advanced disease have all of the features of retinitis punctata albescens.  Also supportive is the fact that mutations in RLBP1 have been identified in both conditions.  

However, many individuals with fundus albipunctatus (136880) are described as having a stable disease with night blindness as the major symptom while many patients reported with retinitis albescens clearly have a more progressive and more serious disease with a fundus picture in late stages resembling retinitis pigmentosa.  The relationship of these two conditions should become clearer once we learn more about the natural history of these rare disorders.