eMedicine Specialties > Ophthalmology > Cornea

Dystrophy, Macular

Author: Natalie Afshari, MD, MA, FACS, Associate Professor of Ophthalmology, Duke University Eye Center, Duke University Medical Center
Coauthor(s): William B Trattler, MD, Ophthalmologist, The Center for Excellence in Eye Care; Volunteer Assistant Professor of Ophthalmology, Bascom Palmer Eye Institute; William Lloyd Clark, MD, Consulting Staff, Palmetto Retina
Contributor Information and Disclosures

Updated: Jan 26, 2010

Introduction

Background

Macular dystrophy is an autosomal recessive condition, which is the least common but the most severe of the 3 major stromal corneal dystrophies. It is characterized by multiple, gray-white opacities that are present in the corneal stroma and that extend out into the peripheral cornea. Examples of macular dystrophy are shown in the images below.

Macular dystrophy. Image courtesy of James J. Rei...

Macular dystrophy. Image courtesy of James J. Reidy, MD, FACS, Associate Professor of Ophthalmology, State University of New York, School of Medicine & Biomedical Sciences, Buffalo, New York.

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Macular dystrophy. Image courtesy of James J. Rei...

Macular dystrophy. Image courtesy of James J. Reidy, MD, FACS, Associate Professor of Ophthalmology, State University of New York, School of Medicine & Biomedical Sciences, Buffalo, New York.


Macular dystrophy.

Macular dystrophy.

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Macular dystrophy.

Macular dystrophy.


Pathophysiology

The cornea is the clear outer coat of the front of the eye. A dystrophy of the cornea is defined as a bilateral noninflammatory clouding of the cornea. Corneal dystrophies can be placed into 3 categories based on their location within the cornea. Anterior corneal dystrophies affect the corneal epithelium and may involve the Bowman membrane. Stromal corneal dystrophies (which include macular dystrophy) affect the central layer of the cornea, the stroma. Posterior corneal dystrophies involve the Descemet membrane and the endothelium.1

Most corneal dystrophies have an onset prior to age 20 years; exceptions include map-dot-fingerprint dystrophy and Fuchs corneal dystrophy. Most corneal dystrophies are dominantly inherited; exceptions are macular dystrophy, type 3 lattice dystrophy, and the autosomal-recessive form of congenital hereditary endothelial dystrophy.

Subgroups of macular dystrophy can be identified by immunohistochemical methods. Keratan sulfate was not detected in the serum of patients with histopathologically confirmed macular corneal dystrophy. Because keratan sulfate in the serum appears to be predominantly derived from the normal turnover of cartilage,2 these studies strongly suggest that the defect in keratan sulfate synthesis in macular corneal dystrophy is not restricted to corneal cells and that this condition is one manifestation of a systemic disorder of keratan sulfate.

Frequency

United States

Macular dystrophy is uncommon.

Mortality/Morbidity

Corneal changes become visible in the first decade of life; a significant reduction in vision usually occurs by age 20-40 years. Eye pain from recurrent corneal erosions can occur but is much less common than in patients with lattice or granular dystrophies.

Sex

No sexual predilection has been reported.

Age

Corneal changes become visible in the first decade of life; vision may be significantly reduced by age 20-40 years.

Clinical

History

  • In many patients, macular dystrophy is first visible in the cornea during the first decade of life.
  • Generally, over time, vision decreases, and patients develop photosensitivity. They may also experience eye pain from recurrent corneal erosions.

Physical

  • Macular dystrophy is characterized by multiple, gray-white opacities that are present in the corneal stroma and extend into the peripheral cornea. (In granular dystrophy, the deposits are located centrally.)
  • These stromal opacities are distributed throughout the cornea without clear spaces. (Granular dystrophy has clear zones.)
  • Macular corneal dystrophy involves the entire thickness of the cornea and is more superficial centrally and deeper peripherally. The central cornea in this condition may be thinned. Significant cornea guttata may be present.

Causes

  • Macular dystrophy is autosomal recessive.
  • The gene responsible for macular dystrophy is located on chromosome 6.
  • The metabolic defect for this condition appears to be an error in the synthesis of keratan sulfate.
  • Two types of macular dystrophy exist based on the absence or presence of keratan sulfate within the corneal stroma. Type I macular dystrophy has an absence of keratan sulfate, whereas in type II, keratan sulfate is present.

More on Dystrophy, Macular

Overview: Dystrophy, Macular
Differential Diagnoses & Workup: Dystrophy, Macular
Treatment & Medication: Dystrophy, Macular
Follow-up: Dystrophy, Macular
Multimedia: Dystrophy, Macular
References
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References

  1. Kannabiran C. Genetics of corneal endothelial dystrophies. J Genet. Dec 2009;88(4):487-94. [Medline].

  2. Quantock AJ, Young RD, Akama TO. Structural and biochemical aspects of keratan sulphate in the cornea. Cell Mol Life Sci. Dec 27 2009;[Medline].

  3. Al-Swailem SA, Al-Rajhi AA, Wagoner MD. Penetrating keratoplasty for macular corneal dystrophy. Ophthalmology. Feb 2005;112(2):220-4. [Medline].

  4. Albert D, Jakobiec F. Principles and Practice of Ophthalmology. Vol 1. 1996:26-49.

  5. Edward DP, Yue BY, Sugar J, et al. Heterogeneity in macular corneal dystrophy. Arch Ophthalmol. Nov 1988;106(11):1579-83. [Medline].

  6. Hafner A, Langenbucher A, Seitz B. Long-term results of phototherapeutic keratectomy with 193-nm excimer laser for macular corneal dystrophy. Am J Ophthalmol. Sep 2005;140(3):392-6. [Medline].

  7. Klintworth GK, Meyer R, Dennis R, et al. Macular corneal dystrophy. Lack of keratan sulfate in serum and cornea. Ophthalmic Paediatr Genet. Dec 1986;7(3):139-43. [Medline].

  8. Krachmer J. Cornea. Vol 2. 1996.

  9. Wirtitsch MG, Ergun E, Hermann B. Ultrahigh resolution optical coherence tomography in macular dystrophy. Am J Ophthalmol. Dec 2005;140(6):976-983. [Medline].

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Further Reading

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Keywords

corneal dystrophy, corneal stroma, anterior corneal dystrophy, stromal corneal dystrophy, posterior corneal dystrophy, corneal dystrophies

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Contributor Information and Disclosures

Author

Natalie Afshari, MD, MA, FACS, Associate Professor of Ophthalmology, Duke University Eye Center, Duke University Medical Center
Natalie Afshari, MD, MA, FACS is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, American Medical Association, American Society of Cataract and Refractive Surgery, and Association for Research in Vision and Ophthalmology
Disclosure: Nothing to disclose.

Coauthor(s)

William B Trattler, MD, Ophthalmologist, The Center for Excellence in Eye Care; Volunteer Assistant Professor of Ophthalmology, Bascom Palmer Eye Institute
William B Trattler, MD is a member of the following medical societies: American Academy of Ophthalmology and American Society of Cataract and Refractive Surgery
Disclosure: Nothing to disclose.

William Lloyd Clark, MD, Consulting Staff, Palmetto Retina
William Lloyd Clark, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Ophthalmology, and Association for Research in Vision and Ophthalmology
Disclosure: Nothing to disclose.

Medical Editor

Fernando H Murillo-Lopez, MD, Senior Surgeon, Unidad Privada de Oftalmologia CEMES
Fernando H Murillo-Lopez, MD is a member of the following medical societies: American Academy of Ophthalmology
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

Christopher J Rapuano, MD, Professor, Department of Ophthalmology, Jefferson Medical College of Thomas Jefferson University; Co-Chairman of the Cornea Service, Co-Chairman of Refractive Surgery Department, Wills Eye Institute
Christopher J Rapuano, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Cataract and Refractive Surgery, Contact Lens Association of Ophthalmologists, Cornea Society, Eye Bank Association of America, International Society of Refractive Surgery, and Pan-American Association of Ophthalmology
Disclosure: Allergan Honoraria Speaking and teaching; Allergan Consulting fee Consulting; Alcon Honoraria Speaking and teaching; Inspire Honoraria Speaking and teaching; RPS Ownership interest Other; Vistakon Honoraria Speaking and teaching; EyeGate Pharma  Consulting; Inspire Consulting fee Consulting; Bausch & Lomb Honoraria Speaking and teaching

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.

 
 
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