autosomal dominant

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.

Folds in the internal limiting membrane are commonly seen, especially in the macula.  Intraretinal edema is seen throughout but may be most evident in the macula which often appears cystic.  Superficial microcystic changes in the retina are concentrated in the posterior pole.  The internal limiting membrane often appears thickened and filamentous material may be present in areas where it is separated from the retina.  The inner retina may have schisis cavities.  Visual acuity remains good until midlife.

This disorder is considered by some to result from a primary defect in Muller cells resulting in permeability defects on the retinal surface.  Evidence for this hypothesis comes from ERG studies in which light adapted responses showed a delayed and reduced b-wave, with broad and delayed ON and OFF responses and a missing flicker response.  However, responses may be inconsistent between the two eyes and more studies are needed.

Histologic studies show endothelial cell swelling, pericyte degeneration, and basement membrane thickening in retinal capillaries.

This disorder is often considered to belong to the category of retinal disease known as flecked retina syndrome.  Further, the nomenclature is not standardized and varying names have been attached to the more or less characteristic fundus picture consisting of uniformly distributed small yellow-white dots in the retina.  These tend to be concentrated in the midperiphery.  The macula usually is not involved in young people although ERG evidence suggests some worsening of cone dysfunction with age and central acuity may be decreased in midlife.  Frank macular degeneration has been seen clinically .  Delayed dark adaptation can be demonstrated with delays in recovery of rod and cone function.  Patients complain of night blindness beginning in childhood with little evidence of progression.

The disease known as retinitis punctata albescens (136880) may or may not be a unique disorder.  It is sometimes grouped with fundus albipunctatus while others consider it to be a separate entity.  Evidence for its uniqueness is based on the progressive nature of field loss and the presence of pigmentary changes and retinal vascular attenuation which are not found in fundus albipunctatus.  Further, the scotopic ERG waveforms usually do not regenerate.  More discriminating studies, especially genotyping, will likely provide additional information.  It would also be useful to have additional follow-up information on families. 

The iris stroma is hypoplastic resulting in a usually dark chocolate color which can suggest the diagnosis at birth.  It may, however, appear slate gray in lightly pigmented individuals.  The pupil is usually normal in morphology and location.  Glaucoma may detectable in the newborn period but it may also not be diagnosed until the 4^th decade or later.  It is widely accepted that the anterior chamber angle is anomalous but the architectural and cellular details are lacking.

Glaucoma often develops in the latter part of the first decade of life but has been diagnosed in the neonatal period.  It affects at least half of patients with IRID1.  The disorder may be suspected in at-risk families by the hypoplasia of the iris stroma resulting in a dark chocolate color with prominent vessels. The irides may also have a dark slate gray color.  Further, the anterior iris surface appears smooth without the usual crypts.  There are no defects in the pigment layer of the iris, and the sphincter is intact while the pupil is in the normal position.  In many patients the iris is inserted anteriorly with numerous iris processes spanning the angle and inserting into the Schwalbe line.  In yet other patients tissue seems to fill the angle obscuring other anatomical structures.

Most reports of Mowat-Wilson disorders provide only incomplete ocular findings and the full phenotype remains to be described.  Most of the reported findings are part of the facial phenotype, such as downward slanting palpebral fissures, and 'wedge-shaped' eyebrows with the medial portion visibly wider than the temporal region.  Hypertelorism, strabismus and telecanthus have also been noted.  However, optic nerve atrophyor aplasia, RPE atrophy, microphthalmia, ptosis, and cataracts are sometimes present while strabismus is more common.  Iris and other uveal colobomas may be present and at least one patient has been reported with retinal aplasia.  There may be considerable asymmetry in the features among the two eyes.