Devices help repair impaired ocular surfaces

September 1, 2012

Prosthetic replacement of the ocular surface ecosystem (PROSE) devices can serve to restore vision, support healing, reduce symptoms, and improve patient quality of life.

Key Points

Baltimore-Prosthetic replacement of the ocular surface ecosystem (PROSE) devices can serve to restore vision, support healing, reduce symptoms, and improve patient quality of life, said Michelle Hessen, OD, here at the 5th annual Evidence Based Care in Optometry conference.

"These devices are FDA-approved custom designed and fabricated prosthetic devices to replace or support an impaired ocular surface," began Dr. Hessen, who is an instructor of ophthalmology, Wilmer Eye Institute, Johns Hopkins Medical School, Baltimore.

Form follows function

"The design of the PROSE device creates a smooth optical surface over irregular, damaged, or diseased corneas. It has an expanded artificial tear reservoir, which provides constant lubrication while maintaining the necessary oxygen supply," Dr. Hessen explained.

Traditional scleral lenses are designed by joining a series of spheres, followed by blending the junctions, she continued. Conjunctival compression may be noted at the area of the junctions. The PROSE devices are designed using spline functions. PROSE devices also use spline function to control vault, and corneal clearance can be adjusted totally independently of the base curve.

"Splines are inherently seamless. There are no junctions to blend. They are created by assembling segments that are shaped by x and y coordinates of a number of points. They can be manipulated to create any desired shape," Dr. Hessen explained.

"Specifically, these PROSE devices can be divided into 8 meridians. One meridian may be changed via the shape of the spline function, totally independent of the other 7 meridians," she added.

"For example, in a patient with a pinguecula nasally in the right eye, the 3-o'clock meridian of the PROSE device can be changed to create an area of elevation so that there is not constant compression of the pinguecula, possibly causing pingueculitis," she said.

But, cautioned Dr. Hessen, PROSE devices are to be used absolutely only as a last resort, mainly due to the intensive fitting process.

"If you think you have a patient that may benefit from the PROSE device, remember that this is a last resort. If the patient is being referred due to an ocular surface disease, they must have exhausted all standard treatments available for dry eye. If they have irregular astigmatism, they should only be considered for PROSE treatment if they are intolerant to or unable to be safely fit with commercial RGPs," she said.

Possible applications

PROSE devices can be used in patients who have irregular astigmatism, such as those with ectasia that may be related to keratoconus, keratoglobus, or post-LASIK ectasia, in addition to those whom have undergone refractive surgery or scarring of the cornea.

PROSE is also indicated for use in patients with dry eye syndrome which may be related to conditions such as chronic graft-versus host disease (cGVHD), Sjögren's syndrome, and rheumatoid arthritis. These devices can also be used in patients with neurotrophic corneas, as related to familiar dysautonomia, acoustic neuroma, trigeminal ganglionectomy, herpes simplex, or herpes zoster. In addition, it can also be used in patients with corneal stem cell deficiencies, epidermal ocular disorders, lagophthalmos, and persistent epithelial defects.