Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Corneal Transplant


Medical Codes

ICD-9-CM:
11.60 - Corneal Transplant, Not Otherwise Specified
11.61 - Keratoplasty, Lamellar, with Autograft
11.62 - Lamellar Keratoplasty, Other
11.63 - Keratoplasty, Penetrating, with Autograft; Perforating Keratoplasty with Autograft
11.64 - Penetrating Keratoplasty, Other; Perforating Keratoplasty (with Homograft)
11.69 - Corneal Transplant, Other

Related Terms

  • Keratoplasty
  • Penetrating Keratoplasty
  • PK

Overview

© Reed Group
Corneal transplant, also known as penetrating keratoplasty (PK), is a surgical procedure that involves replacing the individual's diseased or scarred clear anterior one-third of the eyeball (cornea) with a piece of donor cornea (allograft). The procedure is performed in an outpatient setting, usually under local anesthesia; based on age and comorbidities, some patients may receive general anesthesia, with the consequent need of post anesthesia care.

A corneal transplant is done when an individual's cornea becomes cloudy, scarred, or distorted, preventing light from reaching the interior back surface of the eye (retina) where focusing occurs. Corneal transplants may be performed to alleviate impaired vision or blindness from corneal damage caused by inherited degenerative diseases, infections, ulcers, and physical trauma (e.g., burns, scratches, foreign objects such as metal chips or splinters, fireworks, chemicals).

Corneal transplants typically use human tissue from donor corneas screened for presence of disease, infections, or other abnormalities. In continually developing techniques, artificial corneas (keratoprosthesis) made of flexible plastic may be used for individuals with considerable corneal scarring or who have unsuccessfully undergone previous corneal transplant procedures.

More than 50,000 corneal transplants are performed in the US each year (EBAA).

Source: Medical Disability Advisor



Reason for Procedure

A corneal transplant is considered when the individual's eyesight is significantly impaired by a diseased, scarred, swollen, or otherwise distorted cornea. The procedure usually is considered after drug therapy or other corrective measures to restore the cornea or improve eyesight have failed. In some less severe cases, corneal transplants may be delayed or rendered unnecessary with a procedure called phototherapeutic keratotomy (PTK). PTK involves use of a laser to remove (ablate) and smooth superficial corneal tissue damaged by scarring, disease, or infection. When traditional corneal transplants involving allografts have failed or are inappropriate, a keratoprosthesis may be considered.

Individuals with overly thin tissue in the cornea are at risk of keratoconus (a progressively thinning, abnormal, cone-shaped cornea), distorted vision, and/or corneal rupture, and may require a corneal transplant. Several other conditions are treated with corneal transplant, including ocular herpes virus infections and corneal dystrophies, which include Fuch's dystrophy, lattice dystrophy, map-dot-fingerprint dystrophy, corneal ulcer, and iridocorneal endothelial syndrome. Corneal scarring also may result from injury or as a complication of another surgical procedure.

Source: Medical Disability Advisor



How Procedure is Performed

Corneal transplant surgery is performed in an outpatient setting. Individuals may be given a sedative before the procedure to reduce anxiety. Shortly before the procedure, the surgeon or nursing staff will administer a local anesthetic to numb the eye and control eye movement. In some cases, general anesthesia may be needed. A cookie cutter type surgical instrument called a trephine is used in conjunction with a surgical microscope to remove a full-thickness circle of tissue about 8 mm in diameter from the center of the cornea. The tissue is then replaced with a matching piece of tissue cut from the donor cornea. It is stitched into the recipient's eye with fine, hair-like sutures. The stitches will remain in place until the wound heals properly (from 3 months to up to 2 years) (NKF). A partial-thickness (lamellar) corneal transplant may be performed in some cases. In this procedure, either the inner layer of the cornea (deep lamellar transplant) or outer layer of the cornea (surface lamellar transplant) is replaced (Mayo Clinic).

The individual generally experiences very little discomfort and is released the day of surgery. The individual is instructed to wear a gauze pad over the affected eye, which applies gentle pressure to inhibit post-surgical swelling. An eye shield may be used to protect the eye surface for the first few days after surgery (Mayo Clinic). Ophthalmic eye drops may be prescribed to prevent swelling and infection, as well as to produce paralysis of accommodation (cycloplegics), possibly for as long as several months.

Source: Medical Disability Advisor



Prognosis

Success rates for corneal transplant surgery vary depending on the underlying disease or reason for transplantation but are generally high; corneal transplant surgery ultimately restores at least partial vision in 90% of individuals undergoing the procedure (EBAA). Following corneal transplantation, the individual's vision will be blurred but likely will clear over time. Blurred vision may occur in the area where the stitches were placed, necessitating intervention to tighten or release certain stitches during the healing process (Mayo Clinic). It may take a year or longer for vision to return to normal. During the interim, glasses may be prescribed to help improve vision. Survival rates of grafted corneas tend to decrease between 1 and 5 years. After 5 years, the new cornea survives in about 80% of individuals (Akpek). Following keratoprosthesis, the success rate for transplant retention is 84% for individuals with previous corneal transplant failure and 100% for individuals without previous transplantation attempts (Aldave). Visual outcomes depend largely on underlying health conditions that may affect vision and the presence of complications. Persistent visual problems may be corrected with glasses, contact lenses, or laser eye surgery.

In most individuals, the allograft will heal completely. Rarely, individuals may experience a complication (e.g., rejection, severe infection) resulting in permanent damage. If the procedure was required as treatment for an underlying disease (e.g., corneal dystrophy) the disease could recur and affect the new cornea; a second procedure may be required.

Source: Medical Disability Advisor



Specialists

  • Ophthalmologist

Source: Medical Disability Advisor



Comorbid Conditions

  • Immune system disorders

Source: Medical Disability Advisor



Complications

The primary risk associated with corneal transplantation is allograft rejection, which occurs in approximately 20% of individuals (Mayo Clinic). Rejection typically does not occur during the first 2 months but is possible at any time after that. Signs of impending rejection are redness, sensitivity to light (photophobia), sudden change in vision, and increased eye pain. If these symptoms occur, prompt intervention is crucial to save the transplant. Treatment (usually with corticosteroid eye drops) usually helps to stabilize the cornea and reverse the rejection. Delayed treatment or a particularly severe rejection can cloud the cornea, necessitating another procedure.

Other complications include an increased risk for cataract formation, glaucoma, and corneal swelling. Due to the slow healing rate of the corneal wound, infection is another potential complication. Underlying conditions causing the need for a transplant may recur. In extremely rare cases, corneal transplant has been associated with transmission of the fatal brain disorder Creutzfeldt-Jakob Disease (CJD) from an affected donor to a transplant recipient. Rarely, despite screening, other diseases can be transmitted from donor tissue to the recipient.

Source: Medical Disability Advisor



Factors Influencing Duration

The severity of underlying conditions, presence of complications, and time needed for full recovery will influence duration of disability.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Vision should be evaluated when it is critical to the individual's work assignment. Because the cornea heals slowly, the individual may require reassignment of duties until vision returns to normal. Those who require the use of safety glasses may need to obtain a pair with a corrective prescription. Some individuals may be fitted with a therapeutic contact lens and will be more sensitive to eye irritants, fumes, and dust. Larger computer screens may be helpful if there is decreased in visual acuity in the opposite eye. Eye drops (antibiotics, steroids, cycloplegics) will be needed for a prolonged period after surgery, and accommodations for frequent breaks may be required. Strenuous activities, lifting, and bending will be limited following surgery.

Source: Medical Disability Advisor



References

Cited

Akpek, EK, et al. "Long-Term Outcomes of Combined Penetrating Keratoplasty with Iris-Sutured Intraocular Lens Implantation." Ophthalmology 110 5 (2003): 1017-1022.

Aldave, A. J. "The Boston Type I Keratoprosthesis: Improving Outcomes and Expanding Indications." Ophthalmology 116 4 (2009): 640-651. PubMed. <http://www.ncbi.nlm.nih.gov/pubmed/19243830>.

EBAA. "Frequently Asked Questions." Eye Bank Association of America. 29 Oct. 2009 <http://www.restoresight.org/aboutUS/faq#26>.

Mayo Clinic Staff. "Cornea Transplant." MayoClinic.com. 5 Feb. 2009. Mayo Foundation for Medical Education and Research. 29 Oct. 2009 <http://www.mayoclinic.com/health/cornea-transplant/MY00491>.

NKF. "About Corneal Transplant Surgery." National Keratoconus Foundation. 2009. 29 Oct. 2009 <http://www.nkcf.org/treatment-options/corneal-transplants/69-corneal-transplant-surgery.html>.

General

Jacobs, Jason, and Michael Taravella. "Corneal graft Rejection." eMedicine. Eds. Jack L. Wilson, et al. 25 Sep. 2007. Medscape. 29 Oct. 2009 <http://emedicine.medscape.com/article/1193505-overview>.

Source: Medical Disability Advisor