What are Congenital Retinal Defects?
Congenital retinal defects describe a variety of conditions or abnormalities affecting the retina that are present from birth. The most common congenital retinal defects we see at Retina Consultants of Texas are congenital hypertrophy of the retinal pigment epithelium (CHRPE), coloboma, and persistent hyperplastic primary vitreous (PHPV).
Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE)
Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is a flat, pigmented spot within the outer layer of the retina at the back of the eye. The spot is congenital, meaning that patients who have it are typically born this way. Many CHRPE’s are in the retinal periphery and are difficult to detect without a full retinal exam by a retina specialist so they often go undetected, sometimes until adulthood.
Many CHRPE’s do not change or grow over time. In some patients, the borders of the spot grow very slowly over time, but the spot remains flat. In the majority of patients, CHRPE is a benign finding that never causes a problem with the patient’s vision or life.
If the CHRPE is located in the center of the retina (macula), it can cause patients to have poor vision. But if the spot is in the periphery of the retina, as in most patients, it causes no functional vision loss.
Very very rarely, a true tumor called an adenoma of the retinal pigment epithelium or an adenocarcinoma of the retinal pigment epithelium can arise from a CHRPE. None of these rare patients have ever developed metastases (cancer cells that traveled outside the eye).
A coloboma is a developmental abnormality that leads to a gap or hole in certain parts of the eye. Although iris colobomas are more common, there can also be colobomas of the optic nerve, retina, and choroid. Vision loss is variable, depending on where the coloboma is located and how large of an area is missing. Unfortunately, there is no treatment for coloboma except to maximize vision potential with glasses or contacts. Since colobomas may be found in association with other conditions, such as the CHARGE syndrome or Patau syndrome, it is very important to be evaluated for these as well.
Persistent Hyperplastic Primary Vitreous (PHPV)
During development, the eye is nourished by blood vessels called the primary vitreous. In the third trimester of development, the primary vitreous is no longer needed and normally disappears. When the primary vitreous does not disappear prior to birth, it is called persistent hyperplastic primary vitreous (PHPV).
PHPV can lead to different problems, depending on where it is located. If it involves the front of the eye (anterior PHPV), it can lead to a cataract. If it involves the back of the eye (posterior PHPV), it may cause varying degrees of optic nerve and retinal damage, including retinal detachment. If the cataract is significant, the lens is then removed from the eye to clear the visual axis and allow for some visual recovery.
During lens removal, the state of the retina may also be examined. Generally, the sooner a child is diagnosed with PHPV, the better the chance for visual recovery. If detected very early and if the damage is relatively minimal, PHPV patients can have much better outcomes now than they have had in the past.
Unfortunately, many PHPV patients develop microphthalmia (small eye), and there is a high risk of scar tissue formation, retinal detachment, and glaucoma for which they need lifetime monitoring. If PHPV is only found in one eye it is usually not genetic or associated with any other abnormalities. However, if it is found in both eyes, it may be associated with other developmental disorders and should be further investigated.