OD News Articles

4th January 2019

Dry Eye and Non-cataract Glare

by Tessa Plana, OD Anchorage, AK

The glare of bright lights is a common symptom of cataracts. Here in Alaska where I practice, our winters are especially dark. So many of the patients I see in our clinic complain of glare at night. Although this can mimic a sign of cataracts, examination of the cataractous lens often doesn’t match the severity of symptoms. This is when further investigation is warranted. Evaluation of non-cataract glare and treatment of significant dry eye can improve cataract surgery patients’ expectations and outcomes.

The glare caused by bright lights while driving at night can be a problem.

Glare from Dryness

In colder climates, dry eye in winter months can be exacerbated by two things—environmental dryness and heating systems that blow warm, dry air. Other factors that contribute to dry eye include contact lens use, hormonal changes, autoimmune disease, systemic medications, and ocular trauma. Symptoms vary significantly and can impede the quality of life.

Decreased Vision

A stable and adequate tear film is crucial for clear and non-fluctuating vision. When tears prematurely disintegrate, visual disturbances result, and fluctuating vision can lead to asthenopia.

Clear vision also depends on a smooth corneal surface. So light reflecting off a dry, irregular epithelial surface causes glare. This is often worse at night due to larger pupil size and corresponding higher order aberrations. Studies show that contrast sensitivity is also reduced significantly in patients with dry eye compared with control subjects1,2.

According to a study published in the American Journal of Ophthalmology, people with dry eyes are more likely to have slower response times when driving and are more likely to miss targets—such as crosswalks or potential obstructions in the road3. When patients have cataracts and dry eye, it is vital to discuss residual dry-eye glare and fluctuating vision that cataract surgery won’t resolve.

    A woman with dry eyes rubs her temples.
    A Clue To Dry Eye
    “My vision fluctuates, comes and goes, and bright light bothers me.” Does this sound familiar? Patients and providers may presume cataracts are the cause. But fluctuating vision is a key symptom of dry eye that experts listen for.
Other Non-Cataract Causes of Glare

When symptoms and visual acuity don’t match lens opacity findings, several other conditions may be the culprit:

  1. Uncorrected refractive error can cause halos and glare, especially in under-minused patients or those with astigmatism.
  2. Glasses with scratched lenses or lack of anti-reflective coating may add glare.
  3. Corneal irregularities can produce light scatter. This can be from scars, refractive surgery, Salzmann’s nodules, pterygia, and corneal dystrophies.
  4. Patients with low-grade iritis may interpret photophobia as glare. Before cataract surgery, iritis must be controlled.
  5. Abnormal pupil reactions or shapes, and iris transillumination defects can contribute to glare.
  6. Examining the lens during a routine eye health assessment doesn’t show the amount of spherical aberration that may be distorting vision. As eyes age, optical properties of the crystalline lens change, resulting in overall positive spherical aberration and decreased optical performance4.
  7. Many medications can cause glare, light sensitivity, and blurred vision. Some of the more common include ibuprofen, naproxen, Dilantin, methotrexate, tetracycline, doxycycline, digoxin, amiodarone, atropine, thioridazine, trifluoperazine, cimetidine, ranitidine, and fingolimod5.
Confounding Measurements

Unmanaged dry eye can affect the outcome of cataract surgery by reducing the accuracy of critical measurements.

  • An irregular corneal surface from dry eye will impact keratometry measurements and reduce the accuracy of IOL power selection.
  • Due to challenges in calculating the lens power and aligning the IOL, patients with irregular astigmatism from dry eye are not good candidates for toric IOLs. Even when toric IOLs are optimally aligned, there may be a decrease in visual performance if dry eye is not managed6.

As an aside, dry eye can also compromise quality of vision for those interested in presbyopia-correcting IOLs (extended range of focus or multifocal). A pre-operative evaluation of the ocular surface is advised for all patients considering premium IOLs.

Managing Expectations

For cataract surgery patients to achieve the best possible outcome, dry eye must be under control. For your patients with dry eye, an open discussion about visual expectations after cataract surgery is especially important. It is common for the people we treat to expect not to need glasses after surgery because of their friends’ good outcomes.

Managing these expectations ahead of time will lead to a happier patient—and therefore a happier doctor.

    Irregular Corneal Surface
    irregular corneal surface
    After Treatment
    corneal surface after treatment
Treatment

Treatment for dry eye depends on the severity and cause of dryness. It is often a combination of therapies followed in a step-wise process:

  • Lubrication—preserved artificial tears, preservative-free artificial tears, gels, ointment
  • Meibomian gland therapy—warm compress, lid hygiene, omega-3s, azithromycin, doxycycline, Lipliflow
  • Additional treatments—punctal plugs, topical corticosteroids, Restasis, Xiidra, amniotic membrane tissue, albumin tear supplement
  • Lifestyle modification—humidifier, adequate sleep, don’t sleep with a fan on, CPAP adjustment, lower computer screen, take breaks from screen time
Continued Care

After cataract surgery, dry eye will continue to persist and require management. Symptoms often temporarily get worse with foreign body sensation and irritation. This may take a few weeks or months to subside. Similar to LASIK, cataract surgery may cut corneal nerves that need a few months to regenerate. Surgery also induces ocular inflammation, which may affect tear production and stability. Also, antibiotics in the fluoroquinolone family used after surgery may cause tear film disruption and ocular surface irritation7.

Conclusion

Unmanaged dry eye and non-cataract causes of glare can complicate cataract surgery—and lead to frustrating outcomes. Patients with these conditions may need extra education and guidance on the importance of dry eye care and the possibility that they may continue to be bothered by glare after successful cataract surgery.

Questions

If you ever have questions, feel free to contact any of our optometric physicians. We’re always happy to help.

Reference
  1. https://www.ncbi.nlm.nih.gov/pubmed/16879576
  2. https://journals.lww.com/corneajrnl/pages/articleviewer.aspx?year=1998&issue=07000&article=00006&type=abstract
  3. https://www.healthline.com/health/shut-the-lid-on-chronic-dry-eye/driving#1
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3381094/
  5. https://www.theraspecs.com/blog/medications-side-effect-light-sensitivity/
  6. https://www.healio.com/ophthalmology/optics/news/print/ocular-surgery-news/%7Bed417f32-c3e6-4418-a8ce-03f8e9110b75%7D/accurate-corneal-power-measurements-for-iol-calculations
  7. https://www.reviewofophthalmology.com/article/dry-eye-syndrome-after-cataract-surgery