High Pressure Opthamology

From the May/June 1998 issue of Alert Diver

High-Pressure Opthamology DAN Answers Divers' Most-Asked Questions About Their Eyes

While working with Divers Alert Network as a consultant in ophthalmology over the past three years, I have had the opportunity to respond to many questions from DAN members concerning the eye and diving. This article discusses some of the most frequently asked questions on the topic.

A recent review of this topic entitled "Diving and Hyperbaric Ophthalmology" was published by Butler in the medical journal Survey of Ophthalmology (March/April 1995) and serves as a good additional reference on the subject of the eye and diving.

By Frank K. Butler Jr., Captain, Medical Corps, United States Navy

The Eye and Diving

Our eyes normally exist in a world where the pressure around them is the result of the combined weight of all of the gases in the earth's atmosphere. Diving exposes the eyes to increased pressures. While most of the time this has little or no negative effects on the diver, increased eye pressure in scuba diving can result in ocular decompression sickness and other dysbaric disorders. It may also raise new questions about the management of common eye conditions in divers. The issues discussed here, for the most part, historically have not been well addressed in ophthalmology literature.

1. Is it safe to dive after radial keratotomy?

Radial keratotomy (RK for short) is a surgical procedure designed to cure myopia (nearsightedness). In this operation, the surgeon makes a small number of radially-oriented incisions in the cornea of the eye. These incisions cause a decrease in the strength of the cornea and may increase the risk of serious injury if the eye is subjected to subsequent trauma, including barotrauma such as a facemask squeeze. Despite this theoretical risk, there have been no reports of which I am aware involving a traumatic rupture of the cornea resulting from diving after RK.

Divers who have had this procedure should wait at least three months after the surgery before returning to diving and should be careful to avoid a facemask squeeze - it's important to avoid imposing the "Boyle's Law Stress Test" on these corneal incisions. (See the related article "Diving After Radial Keratotomy" March/April 1996.)

If you are a diver and considering having this procedure done, I would recommend that you also ask your eye surgeon to discuss the potential advantages of photorefractive keratectomy, the alternative refractive surgical procedure discussed below.

2. Is it safe to dive after having had the new laser refractive surgery (photorefractive keratectomy, or PRK)?

3. Diplopia (double vision)

4. Blind spots in your field of vision

5. Pain around the eye

6. Nystagmus (abnormal eye movements)

The presence of any of these symptoms following a dive (except as noted in the next question) should be evaluated as soon as possible by a physician knowledgeable about diving injuries, or the diver should call DAN.

7. I just came up from a dive and noticed that my vision is now blurry. What conditions could cause this symptom?

Possible causes of blurred vision after diving include: a. Contact lenses which become tightly adherent to the eye during a dive. Try using lubricant eye drops to relieve this. b. Displaced contact lens. c. Corneal irritation from mask anti-fog solutions. d. Ultraviolet or "sunburn" damage to the cornea. e. Corneal irritation resulting from bubbles under hard or rigid gas-permeable contact lenses. f. Use of transdermal scopolamine to prevent motion sickness. g. Decompression sickness h. Arterial gas embolism

If you are a contact lens wearer, I would first ensure that the lens is still in place and then instill some lubricant eye drops. If this is successful in restoring your vision to normal, then it is not necessary to seek medical attention. If you are not a contact lens wearer or these actions are unsuccessful, then you should have your symptoms evaluated by a physician knowledgeable about diving injuries. For a list of dive physicians in your area, call DAN.

8. I just came up from a dive and one of my eyes has a bright red spot on it. What could cause this? Do I need to see an eye doctor?

The most common cause of a red spot on the eye after a dive is a subconjunctival hemorrhage. This is a collection of blood over the sclera (white part) of the eye. It is usually caused by a mild facemask squeeze and does not require any treatment. A more severe squeeze could result in other injuries to the eye, however, so it is a good idea to see your eye doctor just in case. It is absolutely essential to see your eye doctor if you have eye pain, double vision, blind spots in your field of vision, or decreased vision after a dive or if you have a history of eye surgery in the past. (See related article, "Mask Squeeze," DAN's Medical Line, July/August 1997.)

9. I am undergoing hyperbaric oxygen (HBO) treatments and have noticed that my vision is slowly getting worse. Why is this happening?

Hyperbaric oxygen therapy may cause a change in the way that the lens of the eye refracts light. This change occurs slowly and is usually not noticed until after a week or two of treatment. If the HBO therapy continues to that point or beyond, the patient may experience a slow myopic (nearsighted) change. This slow change typically continues as long as the HBO treatments continue. It is usually reversible after the treatments are finished, although there have been some reports in which this reversal did not occur or was incomplete.

10. What eye conditions would preclude someone from diving?

a. Gas in the eye (may be present after vitreoretinal surgery). Diving with gas in the eye may result in vision-threatening intraocular barotrauma due to the pressures of the surrounding water column.

b. Hollow orbital implants. The presence of a hollow orbital implant after an eye has been surgically removed because of injury or disease may preclude diving. The increased pressures encountered while diving may cause a hollow orbital implant to collapse, resulting in cosmetic problems and a need for further surgery to replace the damaged implant. Many ocular plastic surgeons are now using implants made of hydroxyapatite, a porous material which is not a contraindication for diving.

c. Acute eye disorders. Any acute eye disorder which produces significant pain, light sensitivity, double vision, or decreased vision is a contraindication to diving. These symptoms may be produced by a number of ocular infectious, traumatic, or inflammatory conditions.

In general, it's best to wait until the underlying acute condition has resolved and there are no distracting or disabling ocular symptoms to contend with before returning to diving.

d. Recent eye surgery. After eye surgery, avoid diving prior to completion of the recommended convalescent period for your particular type of surgery.

e. Inadequate vision. There is a detailed discussion of visual acuity and diving in the article entitled "Diving and Hyperbaric Ophthalmology" mentioned in the introduction.

The recommendation made was that if you see well enough to qualify for a driver's license and operate a motor vehicle safely, then you should be able to see well enough to dive safely.

Deciding on your own visual acuity is primarily a judgment call, with few relevant scientific studies available to help resolve the issue. The approach taken in the article was to use statutory visual standards established for another hazardous activity - driving a car, for example - whose visual requirements are more demanding than diving.

If a prospective diver has visual acuity which is poor enough to preclude him or her from being allowed to drive, then the fitness to dive decision needs to be individualized with the assistance of an eye physician and dive instructor.

f. Decreased vision. If your vision is impaired from previous episodes of decompression sickness or arterial gas embolism, don't risk further injury.

g. Some types of glaucoma surgery (see question #5).

A Final Word

Most of the restrictions to diving mentioned above do not apply to hyperbaric oxygen (HBO) therapy. According to "Diving and Hyperbaric Ophthalmology:"

Hyperbaric exposures in a dry chamber "do not entail immersion of the eye or the possibility of facemask barotrauma. Only the presence of intraocular gas or hollow orbital implants remain as possible ocular contraindications to diving in these patients."

Eye From the MediClip Color Anatomy Collection,
1996, Williams & Wilkins, a Waverley Company