Retinal OCT before cataract surgery increasingly helps guide treatment choices
Screening the retina with OCT rules out preexisting conditions that would affect the outcomes of cataract surgery and helps select candidates for premium IOLs.
“Premium IOLs require a premium macula,” David M. Brown, MD, said. “The optical compromises inherent to multifocal optics make them unsuitable for patients with a less than perfect retina who need all the light and contrast sensitivity they can get.”
Seen on OCT, a “premium macula” shows up as a normal inner and outer retina, a normal foveal depth and normal foveal contour. The ellipsoid band, also known as the inner segment/outer segment (IS/OS) junction, is continuous. The retinal pigment epithelium (RPE) is a straight, thin normal line, and the RPE-Bruch’s membrane band is intact, with no sign of drusen, reticular pseudodrusen or other disturbances, Brown said.
Subtle changes may occur that are not apparent on fundus examination and do not immediately affect vision. Without an OCT, they may go undetected but would still have an impact on the acceptance of a premium lens.
ERM and VMT
“I tell patients that the eye is like a camera and that we’re changing the cloudy lens (the cataract) for a new clear lens (the IOL), but we still need to make sure that the film of the camera (the retina) is healthy and normal in order to get a great picture,” Healio.com/OSN Section Editor Uday Devgan, MD, said.
This applies to not only premium patients but to all cataract surgery patients. The cataract may not be the sole cause of decreased vision, and patients need to have appropriate expectations before surgery.
Epiretinal membrane (ERM) can be difficult to detect with only a slit lamp examination, but it is a common entity. According to data published by Donald M. Gass, MD, it is present in approximately 20% of patients older than 75 years, a portion of the population much larger than expected.
“Even mild ERM significantly increases the risk for postoperative cystoid macular edema, independent of how well surgery is performed,” Devgan said.
Diffractive IOLs should not be used, and an acrylic monofocal may be a wiser choice, particularly if there is a chance that the patient will need a future pars plana vitrectomy.
Vitreomacular traction (VMT) may also remain occult on fundus examination. Because cataract surgery might accelerate posterior vitreous detachment, it is important to identify VMT before the intervention.
“With cataract surgery, we remove a lens that is about 4 mm thick and replace it with an IOL that is approximately 1 mm thick. This may cause the vitreous to shift in the postoperative period,” Devgan said.
AMD and DME
OCT may also detect early features of age-related macular degeneration, such as initial drusen and pigmentary changes.
“It is very important to make the diagnosis before cataract surgery to make an appropriate IOL choice,” OSN Technology Board Member Karolinne M. Rocha, MD, PhD, said.
Wet AMD is a contraindication for presbyopia-correcting IOLs, and so is dry AMD, usually category 3 and 4. Patients with extrafoveal drusen, on the other hand, might still be candidates for extended depth of focus (EDOF) IOLs, in her opinion.
“But they must be made aware that AMD might progress over the years independent of which IOL is used. I had some patients with extrafoveal small, hard drusen implanted with EDOF IOLs, and they are doing great,” she said.
Different is the case of large subfoveal drusen, which are a contraindication. Rocha was recently referred a patient who complained of poor vision with multifocal IOLs. He had one large drusen causing distortion at the IS/OS junction, which was overlooked at the time of surgery.
“It is important to make the diagnosis prior to surgery so you can counsel your patient in advance,” she said. “We sometimes see unhappy multifocal IOL patients who come to our clinic, who underwent surgery, and they are not seeing well. The OCT is a great tool postoperatively to help us understand why they are experiencing problems.”
Diabetic macular edema is another condition that needs to be ruled out when planning the implantation of presbyopia-correcting IOLs.
Screening for DME is “the easiest thing in the world, easier than doing an exam,” Brown said.
“If you are screening for DME or diabetic retinopathy, do an OCT. Even if you don’t get paid, it will save you tons of time. It will give you time to sell that premium IOL to the next patient or see more patients,” he said.
He does not think that diabetes is necessarily a contraindication for multifocal IOLs. Patients with low A1c levels who demonstrate good control are less likely to develop retinopathy. However, patients with higher A1c levels and no real commitment to control have a 10% to 20% chance of developing significant retinopathy within the next 10 years.
“It is all a matter of choosing the right patient and looking well into their condition,” Brown said.
Cystoid macular edema (CME), uveitis, macular dystrophies, scars, RPE atrophy, staphyloma in highly myopic patients and macular telangiectasia should be ruled out as well.
“We see many cases of macular telangiectasia where the retina looks essentially normal but has outer retinal cavitations,” Brown said.
Seeing the unseen
According to Steve Charles, MD, there are two distinct areas that should be carefully scrutinized before surgery: the macula and the periphery.
Peripheral retinal pathologies, more common in myopes, can increase the chances of retinal detachment after cataract surgery. Indirect ophthalmoscopy, supplemented with a wide-angle imaging system, should be performed with a dilated pupil by the ophthalmologist, Charles said. If any retinal breaks are detected, they should be treated with laser before surgery.
The macula, on the other hand, is an insidious territory that may hide a large number of pathologies that are not visible on routine fundus examination.
“As vitreoretinal surgeons, we routinely operate on patients with pathology that is absolutely invisible when looking at the fundus, and we operate based on OCT. Many critical macular conditions, such as vitreomacular schisis, central serous chorioretinopathy, sometimes lamellar macular hole, vitreomacular traction syndrome, small CNV and transparent ERM, are simply invisible without OCT. Some of them we didn’t even know existed until we got this technology,” Charles said.
Charles has spoken at the podium many times to advocate for the use of OCT in every patient before cataract surgery, not just in premium IOL candidates.
“Patient satisfaction counts,” he said. If patients undergo cataract surgery but have a macular disorder that limits their vision postoperatively, they suspect the cataract surgeon is at fault, Charles said.
Treating the pathology, staging surgery
The core problem is pathology that is invisible even to the retina expert. These conditions sometimes need to be treated before surgery and sometimes after surgery.
“The good news is that cataract surgery won’t make macular degeneration worse or vitreomacular schisis worse,” Charles said. “However, once the cataract is out, the case will be handed over to a retinal colleague to deal with the macular problems.”
Cataract surgery should not disrupt a patient’s anti-VEGF injection schedule.
“Rather, do the surgery midway between injections to avoid any question of causation if endophthalmitis, TASS, HORV or sterile inflammation occurs,” Charles said.
Cataract surgery planning should also provide for the staged surgical repair of ERM in coordination with a vitreoretinal surgeon, Devgan said.
As far as VMT is concerned, this should be resolved before surgery.
“There are different ways to address VMT, including vitrectomy and enzymatic vitreolysis, both leading to excellent visual outcome after treatment,” Devgan said.
“Remember that if you predict a problem ahead of time, you are seen as the sharp expert; if you only recognize the problem after it has occurred, you are likely to be blamed for causing it,” he said.
Postoperatively, mild CME is extremely difficult to detect with retinal examination, while it is easy to pick up with OCT, Brown said.
“Postop care is super important. If you know there is some very subtle cystoid macular edema, you can do a slower taper of the postoperative drops and really avoid the rebound CME that can occur if this is missed. A simple OCT postop can really help you there,” he said.
After cataract surgery, OCT monitoring is recommended on a yearly basis in healthy patients, according to Rocha.
“We always explain to our patients, whatever lens we implant, that they need annual follow-up. Age-related conditions, such as AMD and even glaucoma, can develop later in life, and they may need treatment right away. In our clinic, we work closely with retina specialists to treat patients promptly in case we detect anything requiring their expertise,” she said.
A patient implanted with multifocal IOLs who develops macular pathology poses significant challenges. There will be an increasing number of such cases because multifocal IOLs have been implanted now for a number of years in a population that is growing in number and age.
“All you can do is treat the retinal pathology and see how each case develops. Depending on a variety of lifestyle factors, these patients may or may not have complaints. A patient who drives at night a lot may have significant problems due to the development of drusen and reticular pseudodrusen, and there are not a lot of options other than changing the IOL, which can be difficult many years later,” Brown said.
Treatment decisions for patients with multifocal IOLs and macular pathology are made on a case-by-case basis, Rocha said.
“We know that with diffractive lenses — trifocal, diffractive bifocal, even EDOF — the light transmission is less compromised. EDOF lenses are the best in terms of light transmission; they are more forgiving and might be well tolerated also by these patients,” Rocha said.
Adoption is progressing
In retina practice, OCT has become mandatory, and it should be so in cataract practice as well, according to Charles.
“The problem is that cataract surgeons are not so much interested or trained in retina, and they tend to underestimate the importance of including OCT in preoperative testing and looking at it themselves. They are in a hurry doing more than 100 cases a week and often delegate preoperative examinations to an optometrist who has inadequate retina skills,” he said.
Brown, on the other hand, sees that cataract surgeons are now using OCT more or they co-manage with optometrists who have OCT.
“I think there is increasing awareness that OCT is the only way they can pick up pathology that would interfere with the results of surgery. They want patients’ satisfaction to be high and don’t want to disgruntle those who have paid a lot of money for a premium IOL,” he said.
As soon as physicians become familiar with this technology, they realize that it makes the preoperative examination quick and efficient.
“It is easy to learn,” Brown said. “Cataract surgeons can easily look at the foveal reflex and bands and see that everything is normal. If there are questions, they can ask for a retinal consultation, but overall, with a short training, they can handle it.”
One hindrance to adoption in the U.S. is lack of reimbursement. OCT is only reimbursed when used for defining pathology. The cost may be included in the cost of the preoperative assessment when implantation of a premium IOL is planned, but in routine cataract surgery, there is no way to recover the extra cost.
Brown suggested another reason for adopting OCT into routine practice, one that is reimbursable: monitoring patients who are on medications with potentially toxic ocular effects.
“Rheumatologists use a lot of Plaquenil (hydroxychloroquine, Sanofi-Aventis), which may be toxic to the retina. OCT is an easy and effective screening method to detect early signs of toxicity,” Brown said. “Another drug that causes macular toxicity is tamoxifen, which is used in estrogen receptor-positive breast cancer. It is now recommended not just for 5 but for up to 10 years, and we are seeing a lot more retinal pathology. These patients should be screened at least annually, if not every 6 months, once they have passed 5 years on tamoxifen. Other breast cancer drugs can cause cystoid macular edema.”
Offering OCT screening is a way to reach out to internal medicine physicians, rheumatologists and oncologists and help them with an exam they cannot offer themselves or that they were not aware of.
Look at every slice
Charles recommended cataract surgeons not use pseudo-color algorithms, thickness maps or 3D maps, but they should look carefully at every black-and-white slice of every scan.
“Pseudo-color algorithms, thickness maps and 3D rendering look cool but make it harder to interpret the data and often hide crucial pathology. Rather, look at every black-and-white slice yourself,” he said.
Having a technician select a single image for the EMR system is a bad practice, and ophthalmologists should look at all gray-scale B-scan OCT slices.
“The native imaging software from Heidelberg, Zeiss, Optovue, Topcon or whatever OCT system allows you to look at every slice, change the contrast, make measurements and is superfast. You just scroll through the slices with the thumbwheel of your mouse. Don’t say you don’t have time — it takes 5 seconds,” he said.
What at first glance may look like a partial-thickness hole may be seen as a full-thickness hole when scrolling through subsequent images, he said. VMT, macular schisis or subretinal fluid might go missing on a single image. It is commonplace for one, two or three of the slices to show something while the other slices do not.
“So, no color coding and 3D maps. Look at all the slices. Don’t let the technician put them in the EMR program, and look at them yourself. Remember what the core point is. Seen before surgery: preexisting condition; seen after surgery: complication. You can explain to the patient that cataract surgery has not been shown to cause any of these disorders, but the patient will not believe it,” Charles said. – by Michela Cimberle
- Casparis H, et al. Cochrane Database Syst Rev. 2017;doi:10.1002/14651858.CD006757.pub4.
- Ehmann DS, et al. Curr Opin Ophthalmol. 2017;doi:10.1097/ICU.0000000000000331.
- Hirnschall N, et al. J Cataract Refract Surg. 2016;doi:10.1016/j.jcrs.2016.02.029.
- Kowallick A, et al. PLoS One. 2018;doi:10.1371/journal.pone.0208980.
- McKeague M, et al. Curr Opin Ophthalmol. 2018;doi:10.1097/ICU.0000000000000432.
- Moreira Neto CA, et al. Arq Bras Oftalmol. 2015;doi:10.5935/0004-2749.20150062.
- Panozzo G, et al. Eur J Ophthalmol. 2019;doi:10.1177/1120672119830578.
- Pinto WP, et al. J Cataract Refract Surg. 2019;doi:10.1016/j.jcrs.2019.01.022.
- Starr MR, et al. Am J Ophthalmol. 2018;doi:10.1016/j.ajo.2018.05.014.
- Sudhalkar A, et al. Am J Ophthalmol. 2019;doi:10.1016/j.ajo.2018.10.025.
- Tognetto D, et al. Sci Rep. 2019;doi:10.1038/s41598-019-46243-3.
- For more information:
- David M. Brown, MD, can be reached at Retina Consultants of Houston, The Methodist Hospital, 6560 Fannin St., Suite 750, Houston, TX 77030; email: firstname.lastname@example.org.
- Steve Charles, MD, can be reached at the Charles Retina Institute, 6401 Poplar Ave., Suite 190, Memphis, TN 38119; email: email@example.com.
- Uday Devgan, MD, can be reached at Devgan Eye Surgery, 11600 Wilshire Blvd. #200, Los Angeles, CA 90025; email: firstname.lastname@example.org.
- Karolinne M. Rocha, MD, PhD, can be reached at Storm Eye Institute, Medical University of South Carolina, 167 Ashley Ave., Charleston, SC 29425; email: email@example.com.
Disclosures: Brown reports he is a consultant for Heidelberg Engineering, Carl Zeiss Meditec, Optovue and Optos. Charles reports no relevant financial disclosures. Devgan reports he owns and runs CataractCoach.com, which is a free teaching website. Rocha reports she is a consultant for Johnson & Johnson, Alcon and Bausch + Lomb.
Click here to read the Point/Counter to this Cover Story.