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Optical biometry can identify macular pathology before cataract surgery
This can help surgeons pursue further evaluation and better manage patient expectations.
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Historically, ophthalmologists have used optical biometry primarily for the purpose of IOL calculation by obtaining corneal and axial length measurements. Today, with new technology, optical biometry has the potential to provide more than just verifying measurements. It now offers an advantage to physicians by enabling them to identify certain macular pathologies that are, oftentimes, not easily detectable on our slit lamp examination.
When patients have dense or opacified cataracts, it is sometimes difficult to obtain a clear enough view of the macula to confirm a healthy contour when we are discussing IOL options and potential outcomes of surgery with our patients. Optical biometry using swept-source OCT (SS-OCT) now allows imaging across the length of the entire eye, providing a sort of “screening” of the macula. In the following cases, SS-OCT biometry picked up abnormalities of the foveal contour in patients being evaluated for cataract surgery. The scans prompted me to order a standard OCT image, which revealed vitreomacular traction and epiretinal membrane. Here are two instances in which optical biometry saved me from a potential postoperative expectation nightmare.
Case study one
A 76-year-old Caucasian woman was referred to me from an optometrist for a cataract evaluation. Her main complaint was overall cloudy vision with night vision loss. These symptoms were worse in her left eye than in her right eye. Her symptoms had been progressing for more than 1 year, and the referring optometrist felt the cataract was ready to be removed. The patient also had a history of high cholesterol and high blood pressure and was taking medications to treat those conditions. Her visual acuity in the right eye was 20/200 uncorrected and 20/40 best corrected. Her visual acuity in the left eye was 20/100 uncorrected and 20/50 best corrected. Preoperative manifest refraction was +1.50 +0.25 × 166 in the right eye and +1.50 +0.5 × 20 in the left eye.
The cornea demonstrated mild superficial punctate keratopathy with normal-looking keratometry readings in both eyes. The patient was on Restasis (cyclosporine ophthalmic emulsion 0.05%, Allergan). IOP was 13 mm Hg in both eyes. The lenses demonstrated 2 to 3+ nuclear sclerosis and 1+ cortical changes in the right eye and 3 to 4+ nuclear sclerosis with 1+ cortical changes in the left eye. During the retinal examination, I did not identify any significant pathology, although I did not have a good view of the fovea due to the lens.
Source: Inder Paul Singh, MD
The patient was motivated to decrease dependence on glasses because she did not like wearing them. After a long discussion, she agreed to femtosecond-assisted cataract surgery with a multifocal lens in both eyes. She returned for her preoperative visit, and we obtained biometry using SS-OCT (IOLMaster 700, Carl Zeiss Meditec). After the scan, my technician came running into my office asking me why the SS-OCT foveal scan looked “different.” I agreed that something was not right, and I decided to order a standard OCT scan (Cirrus HD-OCT, Carl Zeiss Meditec). To my surprise, we found significant vitreomacular traction (VMT) syndrome tenting up the fovea (Figure 1). This was a shock to me considering I missed it during my examination. Because of this finding, we called the patient and told her to come in to discuss her surgery. We showed her the two scans and let her know we recommended a standard monofocal lens due to her VMT. We also started her on off-label prophylactic topical NSAIDs and told her we would keep her on the NSAID for 3 months postoperatively to help decrease the chances of cystoid macular edema formation. It is important to note both the SS-OCT scan and Cirrus OCT showed a normal healthy foveal contour for the left eye.
This was a huge “save” by SS-OCT. If I had not seen this before surgery, I would have implanted a multifocal lens in a patient with macular pathology, which is not ideal. Furthermore, if we discovered this after surgery, the patient could have the perception that the cataract surgery caused the formation of the VMT. I was also able to better manage her expectations.
The patient was happy after her surgery. Her visual acuity was 20/30 best corrected in the right eye and 20/20 best corrected in the left eye 3 months postoperatively. She still felt that her right eye was not “as sharp” as the left eye and wanted to improve it. We therefore referred her to a retina specialist for a posterior pars plana vitrectomy evaluation. However, she remained happy with our office, and her expectations were set and met.
Case study two
A 72-year-old Caucasian woman was referred for cataract evaluation by a local optometrist. She had complaints of rapidly decreasing vision for 1 year before her presentation. She had non-insulin-dependent diabetes and had received annual retina evaluations by other physicians for more than 10 years. Her glucose measurements were well-controlled during this time. Her HgA1c was 6.8, and she denied any family history of age-related macular degeneration. On examination, her best corrected visual acuity was 20/70 in the right eye and 20/200 in the left eye. The conjunctiva and anterior chamber were quiet, and the cornea revealed mild to 1+ superficial punctate keratitis in both eyes. The lenses revealed 3+ nuclear sclerosis with 1+ posterior subcapsular cataract in the right eye and 4+ nuclear sclerosis with 2+ posterior subcapsular cataract in the left eye. Fundus examination and photography were not clear but did not reveal any obvious edema or retinal hemorrhage near the macula. Left eye fundus photography and examination revealed poor view of maculae details, but there was no obvious macular hemorrhage, exudates or drusen.
I had a hard time seeing the details of the macula in the left eye, and the lens seemed dense enough to explain the poor vision. Before I looked at optical biometry, I assumed the patient would expect to have good postoperative vision in both eyes because I did not see any obvious pathology in the right eye to raise suspicion for postoperative issues in the left eye. She opted for a regular lens with femtosecond-assisted surgery to decrease the amount of phaco energy and reduce a small amount of corneal astigmatism to achieve the best quality of distance vision.
Once I reviewed SS-OCT after the preoperative appointment, I noticed an atypical appearance. There was an “extra line” on the foveal scan. I usually do not see artifacts on foveal scans. I therefore decided to order a traditional OCT image to double check. That image revealed an epiretinal membrane with subtle edema and retinal pigment epithelial changes (Figure 2). These findings on biometry allowed me to follow up and to better set and manage the patient’s expectation. I started her on a topical NSAID and AREDS2 formula (PreserVision, Bausch + Lomb) along with a daily multivitamin because I observed retinal pigment epithelial changes, and the OCT suggested AMD changes as well. I also notified the referring optometrist, so when the patient returned for postoperative comanagement, the optometrist would be fully aware that the patient would need AMD and epiretinal membrane follow-up by us. The patient actually called us back a week after the consult because she had spoken with her relatives and found out that her sister had dry AMD. We therefore provided her with AMD information and helped manage the postoperative care.
Conclusion
Cataract surgeons can now, with SS-OCT biometry, have an added tool to help identify macular pathology ahead of surgery, especially during the consult exam with the patient. Identifying potential pathology on biometry, even in those patients who are not receiving premium technology, helps to pursue further evaluation and therefore better manage expectations. We want to avoid returning patients to their optometrists or having our internal patients return postoperatively when they do not see well after surgery, only for us to then obtain a standard OCT that reveals a macular pathology that should have been identified before surgery. SS-OCT biometry has given me a heightened level of comfort and reassurance. I have changed my protocol to have the biometry scans done at the consult for me to better manage expectations and help patients decide on various premium options.
- For more information:
- Inder Paul Singh, MD, can be reached at The Eye Centers of Racine and Kenosha, 3805B Spring St., Suite 140, Racine, WI 53405; email: ipsingh@amazingeye.com.
Disclosure: Singh reports no relevant financial disclosures.