Proper medical management of any surgery is vital to its ultimate success. Refractive surgery, in particular requires meticulous monitoring, and adapting in order for the individual to achieve the refractive goal set forth. Photo Refractive Keratectomy (PRK) is a common refractive procedure that presents minimal risk, however a risk DOES exist.

PRK involves placing a dish shaped ring on the cornea, and filling it with an alcohol like substance to weaken the top layers of the cornea (epithelial layer). This is followed by a sponge like brush to push away the top layer exposing the inner layers. Next, a laser is used to remove (ablate), and reshape the inner layers of the cornea thereby altering the refractive power of the cornea. A post surgical contact lens is placed on the eye to aid the reepithelialization of the cornea (regenerating of cells that were washed away), and maintain patient comfort during this time period. The average time that the patient must wear the lens is 3-7 days.

During this post surgical period, several prescription eye drops are employed to prevent infection, avoid scarring and reduce pain. Our office prefers to use the antibiotic Zymar to prevent infections, and Xibrom, a non steroidal anti-inflammatory agent, to increase patient comfort. In addition, we prescribe FML steroid to reduce swelling and prevent any scarring during the healing process. While the Xibrom helps with the pain, it also slows down the healing so it is only used for approximately 2 days post surgically. The Zymar will be employed until 2-3 days after the contact lens is removed. Finally, the FML will be instilled for approximately 6 weeks after the procedure.

Patients are instructed to return to the office each day while the contact lens is still in the eyes. During that time we expect to see a gradual healing of the surgically induced abrasion. Unfortunately, on occasion, we notice that the abrasion appears to stop healing. If this continues beyond a few days then there is a good chance that there is a physiological reaction to the medications. While they are prescribed to aid the healing process, some times they actually prevent it. In such cases, we remove the contact lenses and either decrease or stop the drug use. We would not stop the medication prior to 3 days post surgically, but if the healing is too slow, we would discontinue their use afterwards, and tell the patient to use copious amounts of viscous lubrication like Celluvisc. By stopping the medications and keeping the eye very moist, it enables the cornea to heal more rapidly.

After the cornea is healed, we may choose to restart the FML if there is any corneal haze, but not before. In short, special care must be used during the healing process to ensure proper corneal regrowth and modify the treatment regimen as required.

Comments(0)

When a patient walks through the door, the eye care professional must immediately begin evaluating the integrity of that patient; the way s/he carries themselves, their speech pattern, facial features, clarity of their eyes, position of their eyes, signs of squinting, or excessive tearing. These careful observations could alert the practitioner to issues that need attention. The eyes, as we know are the gauges of the inner workings of the body.
The pupils, in particular, characterize the delicate intricacies of the brain, and any abnormalities could prove devastating.

Our basic ocular design is such that both eyes work together in synchrony with each other. That is to say that the eyes are supposed to focus at the same level, move together, process light at the same rate, and both pupils are supposed to react the same to light and accommodation. There are certain conditions that will prevent full symmetrical functioning. For example, the eyes may not move the same way resulting in an eye turn, or one eye may see better then the other resulting in decreased visual functioning. However, the pupils are always supposed to react the same way, at the same time. The one exception to this rule is if an individual is born with this anomaly. Putting that situation aside, all pupils must react identically. If there is a pupil asymmetry, a very serious neurological problem could exist, and that may be life threatening.

To understand how the pupils operate we must first examine the visual pathway. The pupillary reflex starts in the retina. Light enters the eye and is absorbed by the retinal neuroreceptors (similar to camera film); the light then travels through the optic chiasm, the area where the right nerves crosses over to the left, and vice versa. At this junction, the light is split into two pathways on its way to the Lateral Geniculate Body. This is sort of a way station for the optical images sent from the eyes. The next stop on its way is the Edinger-Westfall Nuclei. This is the site where the mechanism that makes the pupils dilate and constrict together is housed. A pupillary anomaly anywhere along this pathway will result in unequal pupillary responses. It should be noted that there are no good causes for a pathway alteration. All are medically serious.

Relative Afferent Pupillary Defects (RAPD) are a serious and troubling finding when examing patients. Most often the eye that has a pupil that does not react properly will have a problem in front of the optic chiasm behind the eye. Some literature has suggested that a dense cataract will prevent light from getting to the retina resulting in a RAPD. However, since even in very dense cataracts some light reaches the retina, most experts will exclude it as a source of a RAPD. The most common source of the problem is optic nerve disease. It should be noted that substantial retinal disease can also result in a RAPD.

Medical conditions such as hypertension and hypercholesterolemia can result in a chocking of the optical nerve blood vessels, which will cause a RAPD. Occasional blurring or fading of vision are common symptoms. These are systemic conditions that must be addressed not only because of the RAPD but as a warning sign of serious medical conditions that can become life threatening. Emboli (blood clots) released by an artery or even the heart can cause RAPD, and may find their way into the brain. Patients suffering from diabetes may have an increased likelihood of presenting the signs of RAPD. Any condition that will result in an inflamed optic nerve can cause an RAPD as well.

The bottom line is any asymmetry in pupil reactions should be addressed immediately, and the appropriate referral must be made in an expedient fashion. Patients noticing any difference in pupil size, or reaction need to contact their eye care professional immediately, without delay. A rapid, proper referral may save the life of an individual.

Comments(0)

The evolution of cataract surgery has changed significantly over the years. It began with simply opening a large wound to remove the cataract, and then closing the hole leaving a void where the natural lens was. The only way a patient could then see was with the aid of very thick post surgical eye glasses. Eventually, contact lenses were developed that would correct the high power required to permit these folks to see well after surgery.

With the invention of the post cataract implant, these thick eye glasses and contact lenses became obsolete. Intraocular implants were initially developed with the goal of correcting distance vision, but still required eyeglasses to permit near vision. As time passed, an implant was needed that would permit both distance and near vision without the need for reading glasses. The first multi focal implant attempts were very poor, and were quickly discarded as useless appliances.

With almost 3 million cataract surgeries being performed annually, and that number expected to double in the next 5-10 years, better alternatives needed to be introduced. A very promising implant that permits both distance and near vision is the Crystalens by Bausch and Lomb. Unlike standard multifocal implants, the Crystalens is an accommodative lens that changes focus as the individual needs to see up close, or far away. It works on the premise that best simulates the natural lens’ ability to accommodate when reading is attempted. That is to say, the lens flexes forward when reading, and backward when viewing in the distance. This implant does however have its limitations. Most surgeons are happy when the implant achieves 20/30 in the distance, and some clarity at near.

This ability for the Crystalens to change focus is accomplished with the aid of the eye’s cilliary body; which pulled on the eye’s natural lens prior to its extraction resulting in its change in thickness. The cilliary body muscle continues to function throughout life and has even demonstrated greater contractile force after cataract surgery. The Crystalens is attached surgically to this muscle to assist in its function.

As this muscle contracts and rotates, the implant flexes and it alters the anterior chamber depth which results in the internal gel of the eye (vitreous) moving forward. Current research has shown that a 1 mm anterior movement will result in an increase of 1.3 diopters in accommodative ability. The Crystalens implant has hinges which allow the implant greater flexibility to move for accommodation.

The Crystalens AT- 45 had a 4.5 mm optic zone, while the Crystalens 5.0 has a 5 mm optic zone. These implants do work quite well, but still received patient complaints of poor near and night vision. The latest development is the Crystalens HD which supports a 5.0 OZ and increases the center thickness to 1.5 mm in the central zone of the lens. This increase in thickness permits a greater arching of the lens and thus better near focusing. The results have been outstanding according to Dr Thierry Hufnagel, a New York eye surgeon at the Stahl Eye Center. This increase in accommodative arching appears to be the answer to better near vision with these post cataract patients.

The FDA’s trial of this lens implant has demonstrated at least 2.OO diopters of accommodation in most patients (enough to read at arm’s length), and as much as 4.00 diopters of accommodation in some of these patients. An additional benefit of this new lens is a decrease in poor night vision as well.

Comments(1)