Cataracts from an Optometric Perspective: What are They, and How Do We Deal with Them? by Leonard Thurschwell, O.D.

A cataract, from an academic perspective, is an opacity or clouding of the crystalline lens that blocks the transmission of light passing through the pupil as it attempts to reach the internal contents of the eye, most notably the retina. From a clinical perspective, it is either a relatively mild condition that may cause minimal deterioration of vision or, if quite pronounced and causing significant visual reduction, may require removal via surgery to ultimately provide the patient with clearer vision.

Causes of Cataracts

Cataracts can develop for the following reasons:

• Congenital – A patient is born with an opacity of the lens in either one or both eyes.
• Trauma – Sustaining a blow to the eye(s) via a physical injury such as that caused by a punch to the eye or perhaps a paint ball or racquetball injury.
• Use of certain drugs (Iatrogenic) – Certain drugs, most notably any kind of steroid (drops, nasal, injectable, or oral) can cause cataracts if used on a chronic basis. A common culprit is prednisone, which is used for many allergic, inflammatory or arthritic conditions.
• Systemic Disease – Conditions such as diabetes or inflammatory diseases may cause or exacerbate cataracts.
• Age – By far, the most common reason for cataract development is age. These can be diagnosed, depending on the person, upwards from age 30. They can be symmetrical — that is, of similar density — or asymmetric, wherein one eye is worse than the other.

Where is a Cataract (Crystalline Lens) Located in the Eye?

A common misconception is that a cataract is a growth over the front surface of the eye causing reduction of vision. There are ocular conditions that can do this which reduce vision minimally or significantly, but these are not cataracts. As mentioned above, a cataract is an opacity of the crystalline lens, an ocular structure located just behind the iris, the colored portion of the eye.

What is the Function of the Crystalline Lens?

The crystalline lens is often compared to a camera lens. It assists in focusing light rays as they enter the eye, hopefully providing a clear image on the retina, which lies at the rear of the eye. It also assists younger individuals in seeing objects up close. The lens accomplishes this by changing its shape, a process referred to as accommodation. When a person reaches 40-45 years of age, he or she starts to develop a condition referred to as presbyopia. The ability of the lens to change its shape is reduced, causing a decrease in the level of near acuity. In these cases, reading glasses may be used to magnify near objects, restoring the individual’s ability to see up close. These glasses can be in the form of reading glasses only or as a combined lens in the form of a bifocal prescription to help with both near and distance vision.

So, What Happens When a Person Develops a Cataract?

When a baby is born, the crystalline lens is transparent, not disturbing any of the light that enters the eye. However, as the individual ages or is subject to other reasons of cataract development, the lens begins to lose its clarity, developing a haze that causes a deterioration of the resulting image formed on the retina. At the beginning, only a change in spectacle or contact lens prescription is needed to reestablish good or acceptable vision. However, as the lens becomes more opacified, the patient’s vision continues to decline and is soon not amenable to improvement from an updated prescription. In addition, patients will start to notice an increase in glare and halos at night, especially when encountering oncoming headlights.

See Dr. Thurschwell’s Full Bio Here

How are Cataracts Diagnosed?

The most important test in diagnosing cataracts involves using a slit lamp (biomicroscope) to look closely at the crystalline lens. A clinician will observe a change in the color of the lens as well as the appearance of numerous opacities in the lens. The most important part of the lens is the region located in the middle, just behind the pupil. This is the part that contributes heavily to the creation of a clear or unclear image as observed by the patient. If the clinician does not feel the patient’s vision is amenable to satisfactory improvement with new corrective lenses, then surgery will be discussed.

What Does a Cataract Surgery Evaluation Entail?

Cataract surgery is an elective procedure. In very few instances is it necessary to perform cataract surgery. However, your optometrist will usually discuss your visual needs and whether a new prescription or surgery is the best option for you. Some older individuals who do not drive, live a very sedate lifestyle, and are still able to do things they need or want to do with limited vision may not want to have cataract surgery. However, younger individuals who still work, continue to drive, travel extensively, or lead very active lifestyles may consider (or even demand) surgery to improve their vision.

If cataract surgery is desired by the patient, a surgical consult with an ophthalmologists will be arranged to cover the specifics of their cataract development. A thorough case history will be taken to see if the patient’s visual complaints justify potential surgery. The patient will then undergo a thorough, dilated evaluation of each eye to categorize the opacification of the lens, inspect other components of the eye, and discuss the type of implants used and the pre- and postoperative care. The ophthalmologist will also discuss with the patient other aspects of each eye which might influence postoperative vision, such as the presence of macular degeneration or diabetic retinopathy. Preoperative protocols and medications, the actual surgical procedure, and what will occur postoperatively will be discussed as well.

How is a Cataract Corrected?

The surgeon will discuss the options available to the patient based on his or her condition. In the past, cataract patients wore thick “cataract” glasses or contact lenses after surgery. Nowadays, intraocular lenses (IOLs) are used to closely simulate — or even improve — vision before the development of cataracts. There are basically three types of IOLs available today:

• Monofocal IOLs – Monofocal IOLs produce clear vision at one distance, either far away or at a patient’s near working distance.
• Toric (astigmatic) IOLs – Toric IOLs are used if a patient has a moderate amount of astigmatism and the surgeon feels a patient’s vision cannot otherwise be adequately corrected.
• Multifocal IOLs – Multifocal IOLs are used to provide a patient with clear vision at both distance and up close.

A common question that we, as primary eye care providers, often hear is “Will I need to wear glasses after cataract surgery?” The answer is that in most cases a pair of glasses may be necessary to improve visual clarity in some circumstances. In some cases, a patient’s postoperative vision is excellent at their desired near and distance ranges and they can avoid wearing glasses, but this is usually the exception rather than the rule. At the last postoperative visit, usually about one month after surgery, your doctor will discuss with you whether you would like continue wearing glasses.

Cataract surgery is the most common surgical procedure. The results are excellent, and the surgeons at the Marietta Eye Clinic are all experts at providing their patients with the best options to suit their patients’ lifestyles. The visit with the ophthalmic surgeon is relatively long so that all aspects concerning the surgery, discussed above, are addressed to the satisfaction of the patient.

More About Ocular Disease Specialist Leonard Thurschwell, O.D.

Dr. Thurschwell is a primary care optometrist with the Marietta Eye Clinic who also provides ocular surgery co-management. He earned his doctor of optometry from the Pennsylvania College of Optometry. He is a member of the American Academy of Optometry, the Georgia Optometric Association, and the American Optometric Association. He has had his research published in the Southern Journal of Optometry and the Journal of the American Optometric Association. Read more about him in his bio.

References and Additional Resources

The American Academy of Ophthalmology (AAO) is the world’s largest association of eye physicians and surgeons. It describes itself as a “global community of 32,000 medical doctors who protect sight and empower lives by setting the standards for ophthalmic education and advocating for our patients and the public.” Its website is a great resource to learn more about how to care for your eyes.

The American Optometric Association (AOA) describes itself as the leading authority on quality care and an advocate for our nation’s health, representing more than 44,000 doctors of optometry, optometric professionals, and optometry students.