Neovascularization, Corneal, CL-related 

  • Author: Barry A Weissman, OD, PhD, FAAO; Chief Editor: Hampton Roy Sr, MD   more...
 
Updated: Jul 13, 2011
 

Background

The normal cornea is transparent and maintains itself as an immune privileged site, in part because it is avascular. Ocular insult, including infectious keratitis, immunological conditions, corneal trauma, alkali injury, and contact lens wear (CL),[1, 2] can encourage new blood vessels to grow from the limbus and, hence, neovascularization (NV). NV is generally accompanied with an inflammatory response and always represents a state of disease.

With CL wear, superficial NV is more common than deep stromal vessels. It is speculated that deep stromal NV may reflect a more profound insult (hypoxia) compared to that which generates only superficial NV. Both superficial and deep stromal NV are reported with the use of hydrogel, hard (polymethyl methacrylate [PMMA]), and rigid gas permeable CLs, especially with a history of aphakia, extended wear, poor compliance, and poor follow-up care.[3] Deep stromal NV is serious, possibly leading to loss of optical transparency of the tissue through stromal hemorrhage, scarring, and lipid deposition.

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Pathophysiology

NV is believed to result from an inflammatory or hypoxic disruption of an exquisitely balanced corneal immune system.[4, 5, 6] Hydrogel, hard, and rigid gas permeable CLs stimulate NV by either mechanically irritating the limbal sulcus or by creating corneal hypoxia, which leads to limbal inflammation, epithelial erosion, or hypertrophy, and, hence, angiogenic mediator release.[7]

Epithelial trauma[8] and/or hypoxia[9] may stimulate production of angiogenic factors by local epithelial cells, keratocytes, and infiltrating leukocytes[10, 11] (eg, macrophages, neutrophils). Some of these factors (ie, acidic and basic fibroblast growth factors, interleukin 1 [IL-1], and vascular endothelial growth factor [VEGF]) have been identified and isolated from cornea and tears. Angiogenic factors[12] stimulate a localized enzymatic degradation of the basement membrane of perilimbal vessels at the apex of a vascular loop. Vascular endothelial cells migrate and proliferate to form new blood vessels.[13]

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Epidemiology

Frequency

United States

Prevalence among CL wearers is 1-30%; prevalence is lower in those who wear (rigid) gas permeable lenses than in soft CL wearers.[14] There is an increased risk for patients who have high myopia, dry eyes, or ocular surface disease (eg, idiopathic or associated with other diseases, such as acne rosacea, Sjögren syndrome, and immune dysfunction). There is also an increased risk in those who use extended wear hydrogel CLs and in those who use aphakic or therapeutic CLs.

Silicone hydrogel CLs with oxygen permeabilities approaching 100-200 Fatt Dk units have decreased the incidence of corneal NV among CL users.

Mortality/Morbidity

This condition is not associated with mortality. Symptoms can range from asymptomatic and mild to severe with loss of vision. NV in the cornea's visual axis can threaten visual function directly or through secondary hemorrhage,[15] scarring, or lipid deposition.

Incidence of subsequent corneal graft rejection is estimated by one study to be 1.7 times higher in a setting of vascularized rather than nonvascularized host corneas. Risk and severity of a graft rejection is believed to depend upon the depth and extent of NV; hence, deep stromal vessels incur more risk than superficial pannus, and the more quadrants involved, the higher the risk of rejection.[16]

Race

No ethnic predilection exists.

Sex

No gender predilection exists.

Age

NV can occur and progress at any age.

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Contributor Information and Disclosures
Author

Barry A Weissman, OD, PhD, FAAO  Chief of Contact Lens Service, Professor, Department of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, David Geffen School of Medicine; Adjunct Professor of Optometry, Southern California College of Optometry

Barry A Weissman, OD, PhD, FAAO is a member of the following medical societies: American Academy of Optometry, American Optometric Association, California Optometric Society, and International Society for Contact Lens Research

Disclosure: VSP None Speaking and teaching; Alcon None Speaking and teaching; Vistakon/The Vision Care Institute Grant/research funds support of Fellowship program

Coauthor(s)

Karen K Yeung, OD, FAAO  Director of Optometry, Arthur Ashe Student Health and Wellness Center, University of California at Los Angeles

Karen K Yeung, OD, FAAO is a member of the following medical societies: American Academy of Optometry

Disclosure: Nothing to disclose.

Specialty Editor Board

Andrew W Lawton, MD  Medical Director of Neuro-Ophthalmology Service, Section of Ophthalmology, Baptist Eye Center, Baptist Health Medical Center

Andrew W Lawton, MD is a member of the following medical societies: American Academy of Ophthalmology, Arkansas Medical Society, and Southern Medical Association

Disclosure: Nothing to disclose.

Simon K Law, MD, PharmD  Associate Professor of Ophthalmology, Jules Stein Eye Institute, University of California, Los Angeles, David Geffen School of Medicine

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.

Christopher J Rapuano, MD  Professor, Department of Ophthalmology, Jefferson Medical College of Thomas Jefferson University; Director of the Cornea Service, Co-Director 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; Bausch & Lomb Consulting fee Consulting

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.

References

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