16 Oct Are Dilating Drops Always Necessary?
Well, yes. It is always necessary to dilate the pupil for a thorough exam of the retina. A dilated pupillary exam is part of a thorough examination of the eye. Without dilation, it is near impossible to see any structures of the retina through the tiny, 2-3 mm, undilated pupil.
All my patients need to be dilated because I am a retinal specialist. Most of my patients have macular degeneration or diabetic retinopathy. Without dilation I could not examine the retina properly.
As part of the initial screening when a patient arrives at the office, dilating drops are instilled into one or both eyes. The patients are then escorted to a separate “dilating” room. Patients may read, watch TV or talk until dilation occurs. Usually this takes about 15-20 minutes, bur variations do occur. Once the pupils are dilated, patients are then moved to an examination room and we complete the office visit by examination with me, the doctor.
Why do the drops take so long to work? There are a few reasons for the varying times a patient may wait before complete dilation. There are both physiologic reasons and practical reasons.
Physiologic reasons include the patient’s age and the color of their eyes (color of the iris). Young patients with darkly pigmented (e.g. brown eyes) eyes take the longest to dilate. They are slow dilators. Why? The muscles that need to be relaxed by the dilating drops are the strongest at younger ages. Also, the pigment in darkly colored eyes absorbs the dilating medicine and, thus, it takes longer for the medicine to exert its effect.
I don’t discriminate, but the dilating drops do. The corollary to the slow dilator is that blue eyed, older patients do not take much time to dilate at all. Sometimes this may be as fast as 5-10 minutes. You can imagine the nasty looks I sometimes get as I am seeing patients out of turn, simply because some patients dilate faster than others.
There are some diseases or situations where dilation also takes a lot longer than normal. Some patients simply don’t respond well to the drops. Patients with uveitis (inflammation inside the eye) also take a long time to dilate.
Sometimes I cheat by having some of my patients arrive dilated. I don’t suggest this for a routine exam because it is often very difficult to accurately assess vision. After I operate, I usually instill dilating drops in the operating room. Patients arrive to the office, the next day, already dilated. The exam is usually very brief.
There are practical reasons for longer dilating times. Occasionally, doctor’s offices run behind. I try to run my schedule as fast and efficiently as possible, but sometimes we can’t do it. On occasion, we might blame slow dilating for the reason for a longer waiting time. (Ok, don’t quote me on this one or I’ll deny it.)
Others ways to examine the retina are available, but none as good as a dilated exam allowing direct visualization of the retina. Ultrasound may be used to determine if the internal structures are in the right position. A retinal detachment, for example, may be diagnosed by ultrasound.
Non-dilating (so called non-mydriatic) cameras are available. These devices are able to take pretty good pictures of the retina through an undilated pupil. They are quick and used for screening purposes. If an abnormality is seen, then a complete dilated exam is warranted. It is not good enough for the detailed examination required for patients with diabetic retinopathy or macular degeneration.
In conclusion, fully dilated examination is essential to a proper exam of the retina. Other techniques just don’t provide the information we get by directly viewing the retina. It does take a longer time, and at our office we warn each patient about the necessity of dilation.
Thanks for your patience.
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist