eMedicine Specialties > Ophthalmology > Intraocular Pressure

Glaucoma, Primary Congenital

Gerhard W Cibis, MD, Clinical Professor, Director of Pediatric Ophthalmology Service, Department of Ophthalmology, University of Kansas, Kansas City
Robert C Urban, Jr, MD, Medical Director, Glaucoma Associates, Oaklake Medical Center; Andrew A Dahl, MD, Director of Ophthalmology Teaching, Mid-Hudson Family Practice Institute, The Institute for Family Health; Assistant Professor of Surgery (Ophthalmology), New York College of Medicine

Updated: Feb 13, 2009

Introduction

Background

By definition, primary congenital glaucoma is present at birth; however, its manifestations may not be recognized until infancy or early childhood. It is characterized by improper development of the eye's aqueous outflow system, leading to increased intraocular pressure (IOP), with consequent damage to ocular structures, resulting in loss of vision. Although the disease is relatively rare, the impact on visual development can be extreme. Early recognition and appropriate therapy of the glaucoma can significantly improve the child's visual future.

Pathophysiology

Primary congenital glaucoma is restricted to a developmental abnormality that affects the trabecular meshwork. This serves to distinguish it from other childhood glaucomas associated with other ocular and systemic congenital abnormalities, as well as childhood glaucomas that may be secondary to other ocular disorders, such as inflammation, trauma, and tumors.

Frequency

United States

Primary congenital glaucoma is estimated to affect fewer than 0.05% of ophthalmic patients, although patients with the disease account for a significantly higher incidence in institutions for the blind, with various studies suggesting from 2-15%.

Mortality/Morbidity

The disease is bilateral in approximately 75% of cases.

Race

Congenital glaucoma affects all races

Sex

Male patients are found to have a higher incidence of the disease, comprising approximately 65% of cases.

Age

Primary congenital glaucoma usually is diagnosed at birth or shortly thereafter, and most cases are diagnosed in the first year of life.

Clinical

History

The classic triad of manifestations, any one of which should arouse suspicion of glaucoma in an infant or young child, includes epiphora, photophobia, and blepharospasm.

Physical

Complete ophthalmologic examination

Externally, changes within the cornea, especially within the first few years of life, provide strong additional support for the diagnosis.
The average horizontal corneal diameter at birth is less than 10.5 millimeters. Distention of the globe in response to elevated intraocular pressure leads to enlargement of the cornea. If the corneoscleral junction is more than 12 millimeters in diameter in the first year of life, it is highly suggestive of glaucoma. Grossly, this is more evident in asymmetric cases.
Corneal edema may be a direct result of the elevated intraocular pressure, producing a corneal haze that clears with normalization of the pressure. Haab striae represent tears in the Descemet membrane as a result of elevated intraocular pressure. In advanced cases, a dense opacification of the corneal stroma may occur secondary to the corneal edema, and it may persist, despite reduction of the intraocular pressure.
The early presence of glaucoma may deepen the anterior chamber. Because of the frequent occurrence of iris abnormalities in many types of both primary and secondary childhood glaucomas, the iris and angles always should be studied carefully and with thorough gonioscopy.
By the time that glaucoma is diagnosed in a child, the optic nerve head is usually abnormal. Variable cupping is present, usually annular in form, with nasalization of vessels and preservation of the well-vascularized rim. Pallor is first seen temporally when present at an advanced stage.
Tonometry often can be accomplished in a child's eye with a handheld instrument, such as a Perkins tonometer or a Tono-Pen. Accuracy of intraocular pressure measurements taken in the office may be artificially elevated from straining.

Causes

Most cases of primary congenital glaucoma are sporadic in occurrence. However, evidence exists suggesting that the disease may be transmitted through an autosomal recessive pattern, with variable penetrance, or a polygenic inheritance pattern.

CYP1B1, the gene encoding cytochrome P4501B1 (P450, family I, sub family B, polypeptide 1) is associated with primary congenital glaucoma. GLC3B located on band 1p36 and GLC3C located on band 14q24.3 are loci that are linked to primary congenital glaucoma, but the genes are unknown.

The incidence of CYP1B1 in familial cases is 93% in Saudi Arabia, 50% in Brazil, and 20-30% in ethnically mixed populations, and its incidence in nonfamilial (simplex) cases is 10-15%. Mice with this defect have structural abnormalities of the drainage system resembling those seen in humans.

Differential Diagnoses

Peters Anomaly

Workup

Laboratory Studies

Laboratory methods of diagnosing primary congenital glaucoma include the following:

Hybridization analysis using hybridization of a mutant nucleic acid probe to the CYP1B1 gene
Direct mutation analysis by restriction digest
Sequencing of the CYP1B1 gene
Hybridization of an allele-specific oligonucleotide with amplified genomic DNA
Identification of the presence of mutant proteins encoded by the CYP1B1 gene

Imaging Studies

High-resolution anterior segment optical coherence tomography

Other Tests

Examination under anesthesia can supply important information about the childhood patient.
- In addition to tonometry, corneal measurements, gonioscopy, and ophthalmoscopy should be performed in the operating room and carefully documented.
- Intraocular pressures recorded under general anesthesia are usually lower than those obtained in the office because of the effects of the anesthetic agents. In unilateral cases, asymmetry of otherwise normal intraocular pressures may be diagnostic, along with other signs, such as corneal diameter.
- If available in the operating room, pachymetry to quantify corneal edema and A-scan ultrasound to determine axial distention often are useful.¹
- Multiple examinations may be needed before a definitive diagnosis can be made.

Treatment

Medical Care

Primary congenital glaucoma almost always is managed surgically. Medical therapy is used only as a temporizing measure prior to surgery and to maximize pressure control after surgery.

Surgical Care

The primary surgical techniques are designed to eliminate the resistance to aqueous outflow created by the structural abnormalities in the anterior chamber angle. This may be accomplished through an internal approach with goniotomy or through an external approach with trabeculotomy.

Goniotomy is a technique in which abnormal tissue is incised under direct visualization with the aid of a goniolens. This presumably relieves the compressive traction on the anterior uvea on the trabecular meshwork, which eliminates any resistance imposed by incompletely developed inner trabecular meshwork.
Viscotrabeculotomy (canalotomy) uses a high-viscosity viscoelastic to open the canal.²
In trabeculotomy, the Schlemm canal is identified by external dissection, and the trabecular meshwork is incised by passing a probe into the canal and, then, rotating it into the anterior chamber. One advantage of this procedure is that it can be performed in eyes with cloudy corneas, which is not the case with goniotomy.
Both goniotomy and trabeculotomy have their advocates; however, reported success rates for both procedures are approximately 80%. The worst prognosis occurs in infants with elevated pressures and cloudy corneas present at birth. The most favorable outcome is seen in infants operated between the second and eighth month of life. Surgery has been found to be less effective in preserving vision, with increasing age.
When multiple goniotomies and/or trabeculotomies have failed, the surgeon usually resorts to a filtering procedure, such as trabeculectomy. This may be accomplished either with or without antimetabolites. Should these procedures fail, shunts may be used. In those situations, in which all else has failed, ciliary body destructive procedures may be useful.

Follow-up

Further Outpatient Care

The follow-up care of patients with primary congenital glaucoma has several important facets. In the early postoperative period, close observation is required regarding success of the procedure. This may require multiple examinations under anesthesia.

Complications

Serious complications of surgical intervention include hyphema, infection, lens damage, and uveitis.
The most serious complications in children often are caused by general anesthesia. Because of anesthetic risks, bilateral procedures are indicated in some children.

Prognosis

Corneal edema may persist for weeks after successful reduction of the intraocular pressure. Changes in the optic nerve head provide the most important indicator of the course of the disease. Cupping can reverse in successfully treated cases.
The intraocular pressure also is a significant factor in postoperative visual capacity, with substantially better vision among those patients whose pressures remain no higher than 19.
- Even when the intraocular pressure is well controlled, approximately 50% of children do not achieve vision better than 20/50.
- Reduced visual acuity may result from persistent corneal edema, nystagmus, amblyopia, or large refractive errors.

Patient Education

The patient and family must understand that intraocular pressure elevation can recur at any age in individuals with primary congenital glaucoma, and these patients must receive follow-up care throughout their lives.
For excellent patient education resources, visit eMedicine's Glaucoma Center. Also, see eMedicine's patient education articles Primary Congenital Glaucoma and Glaucoma Overview.

Miscellaneous

Medicolegal Pitfalls

Since most of these patients are preverbal children, it is extremely important to thoroughly investigate any suspicious clinical findings.

References

Gupta V, Jha R, Srinivasan G, Dada T, Sihota R. Ultrasound biomicroscopic characteristics of the anterior segment in primary congenital glaucoma. J AAPOS. Dec 2007;11(6):546-50. [Medline].
Tamcelik N, Ozkiris A. Long-term results of viscotrabeculotomy in congenital glaucoma: comparison to classical trabeculotomy. Br J Ophthalmol. Jan 2008;92(1):36-9. [Medline].
Bejjani BA. Primary congenital glaucoma. Gene Tests. Available at http://www.genetests.org/. Accessed September 30, 2004.
DP Edward, Fajarananant TS, et al. A comprehensive update on congenital glaucoma. Current Pediatric Reviews. Feb 2008;4(1):19-30.
Sarfarazi Mansoor , inventors; U of Connecticut. Diagnosis of Primary Congenital Glaucoma. US patent 6207394. March 27 2001.

Keywords

primary congenital glaucoma, childhood glaucomas, glaucoma in children, increased intraocular pressure, increased IOP, optic nerve damage, vision loss, blindness, aqueous outflow

Contributor Information and Disclosures

Author

Gerhard W Cibis, MD, Clinical Professor, Director of Pediatric Ophthalmology Service, Department of Ophthalmology, University of Kansas, Kansas City
Gerhard W Cibis, MD is a member of the following medical societies: American Academy of Ophthalmology, American Association for Pediatric Ophthalmology and Strabismus, and American Ophthalmological Society
Disclosure: Nothing to disclose.

Coauthor(s)

Robert C Urban, Jr, MD, Medical Director, Glaucoma Associates, Oaklake Medical Center
Robert C Urban, Jr, MD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Ophthalmology
Disclosure: Nothing to disclose.

Andrew A Dahl, MD, Director of Ophthalmology Teaching, Mid-Hudson Family Practice Institute, The Institute for Family Health; Assistant Professor of Surgery (Ophthalmology), New York College of Medicine
Andrew A Dahl, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology, American College of Surgeons, American Medical Association, American Society of Cataract and Refractive Surgery, and Wilderness Medical Society
Disclosure: Nothing to disclose.

Medical Editor

Neil T Choplin, MD, Adjunct Clinical Professor, Department of Surgery, Section of Ophthalmology, Uniformed Services University of Health Sciences
Neil T Choplin, MD is a member of the following medical societies: American Academy of Ophthalmology, American Glaucoma Society, Association for Research in Vision and Ophthalmology, and California Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

Simon K Law, MD, PharmD, Assistant Professor of Ophthalmology, Jules Stein Eye Institute; Chief of Section of Ophthalmology Surgical Services, Department of Veterans Affairs Healthcare Center, West Los Angeles
Simon K Law, MD, PharmD is a member of the following medical societies: American Academy of Ophthalmology, American Glaucoma Society, and Association for Research in Vision and Ophthalmology
Disclosure: Nothing to disclose.

Managing Editor

Martin B Wax, MD, Clinical Professor, Department of Ophthalmology, University of Texas Southwestern Medical School; Vice President, Ophthalmology Research and Development, Head, Ophthalmology Discovery Research, Alcon Labs, Inc
Martin B Wax, MD is a member of the following medical societies: American Academy of Ophthalmology, American Glaucoma Society, and Society for Neuroscience
Disclosure: Alcon Labs Salary Employment

CME Editor

Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri
Disclosure: Nothing to disclose.

Chief Editor

Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology
Disclosure: Nothing to disclose.

Further Reading