Preoperative Workup and IOL Recommendations From Optometrists

With the power of recommendation comes the responsibility of education.

By Shalu Pal, OD

Our patients count on us—their optometrists, their primary eye care providers—to offer credible, honest, safe recommendations in all areas related to eye care. When they are in need of surgery, our patients look to us for guidance and support, which may not be offered by surgeons due to their time constraints and packed schedules.

For patients in need of surgery, then, our role as optometrists is to provide empathy, reassurance, and, most important, enough information to help make the best decisions possible. With this role comes responsibility, because we can greatly influence the timing of surgery and the surgical options chosen. Time spent with an optometrist is one of the major factors influencing patients’ overall experience of cataract surgery.1

TO THE POINT

Optometrists have the ability and the responsibility to guide their patients through the process of preparing for cataract surgery.

Cataract surgery is an invasive procedure that can be intimidating to many. Often, it is the patient’s first experience with surgery. Many options must be weighed before the patient chooses a surgical center or implant type.

With the increasing visual demands of our patients due to their active, busy lifestyles, I find myself discussing the impact of cataracts and the options for cataract surgery much earlier in the disease process than I did in the past.

When I discuss cataracts with my patients, I address several frequently asked questions:

• What are cataracts, and how do they affect vision?
• What is cataract surgery, and when is it an option?
• What are the preoperative and postoperative protocols and associated costs?
• What are my options related to the surgery?

This article relates some of the ways I interact with patients to prepare them for the experience of cataract surgery.

EXPLAINING SURGERY

Over the years, my way of explaining cataracts has evolved from reliance only on words to the use of models and pictures. My description of the actual procedure has changed, too, as the surgery itself has become much more advanced. I tell patients that, today, many surgeons use a femtosecond laser, with guidance from intraoperative optical coherence tomography (OCT) imaging, to create the circular opening in the anterior capsule, to precisely fragment the lens, and to create the corneal incisions the surgeon uses to access the anterior chamber.2 Imaging systems and tracking algorithms can track eye position and cyclotorsional movements of the eye when patients move from sitting to lying down.3 During surgery, measuring the wavefront of the eye after the lens has been removed can help to improve the calculations used to determine the optimal IOL power. IOL power calculations can be tougher in certain eyes, including those that have had previous corneal refractive procedures and those with high levels of posterior corneal astigmatism.4

As I describe the surgical process, I explain the preoperative testing that will be done in my office and the further IOL calculations and testing that will be done at the patient’s initial consultation with the surgeon’s team. I also discuss the postoperative schedule of 1 day, 1 week, and 1 month follow-up visits and the need for an intensive postoperative drop regimen. All costs involved with these tests are described and outlined in our initial conversations.

I explain that my preoperative workup will include several tests that must be done before referral of the patient to a surgeon. In addition to a comprehensive eye exam, I perform the following tests:

• Retinal imaging and baseline OCT;
• Corneal topography;
• Lid and lash evaluation;
• Dry eye workup.

OCULAR AND SYSTEMIC HEALTH

An understanding of the patient’s systemic and ocular health is important to be able to properly recommend surgical IOL options. Patients with glaucoma and macular degeneration are at higher risk for complications such as glare and halos. Patients with systemic conditions such as diabetes can have a higher risk of postsurgical edema. Cornea guttata may be a factor preventing surgery.5 All of these elements are examined in my initial workup.

TOPOGRAPHY

Corneal topography is an extremely valuable tool to both the optometrist and the surgeon prior to cataract surgery. Topography allows us to look for corneal irregularities such as keratoconus and high levels of astigmatism. It also helps to differentiate between corneal and lenticular astigmatism, by comparing the patient’s topographic astigmatism with his or her refractive astigmatism. For the surgeon, it helps to better understand the cornea, where corneal incisions for surgery should be placed, and how best to calculate IOL power.6

EXTERNAL EVALUATION

The risk of endophthalmitis is very low, with reported incidence rates of 0.06% to 0.09%, but it is still a concern that must be mitigated as thoroughly as possible due to the devastating nature of the complication.7 The offending agents in acute postoperative endophthalmitis are generally microorganisms resident in the eyelid margin, conjunctiva, and tear film.7 We can dramatically reduce this natural microbiota by cleaning the lids and lashes to eliminate any signs of blepharitis. This is accomplished with lid wipes, hot compresses, and novel treatments such as the BlephEx in-office procedure (Rysurg). Cleaning the ocular adnexa prior to surgery is an important complementary prophylactic approach to reducing the risk of endophthalmitis.

DRY EYE EVALUATION

There are two main reasons why dry eye conditions must be addressed before referral in all cataract surgery candidates. First, it is well documented that cataract surgery will increase the severity of existing dryness by one step postoperatively.8 By addressing any existing disease preoperatively, we can reduce postoperative complaints of dry eye significantly.

Second, and probably the most important reason for dealing with patients’ dry eye signs and symptoms before surgery, is that the determination of IOL power depends on a clean and healthy ocular surface. Eye care providers are less likely to encounter IOL power miscalculations when working with a healthy cornea and tear film prior to surgery. This is especially important with premium IOLs.9,10 Studies have shown that the use of topical cyclosporine ophthalmic emulsion 0.05% (Restasis, Allergan) preoperatively can improve visual performance with multifocal IOLs.9

Simply stated, vision starts with the tear film. Improving the tear film improves the quality of vision after IOL implantation. This, in my opinion, is one of the most important steps we can do to help optimize our patients’ visual outcomes.

IOL OPTIONS

A key point of preoperative discussion with patients is to determine the type of IOL they are interested in having implanted into their eyes. There are several visual options available to patients today:

• Best distance or near correction with monofocal IOLs;
• Monovision with monofocal IOLs;
• Best distance and near correction with premium IOLs.

It is important to communicate ideas clearly and set realistic expectations in our patients. Despite major advances in cataract surgery and biometric measures, only an estimated 55% of patients reach their refractive target postoperatively. Approximately 40% of patients are dissatisfied with their visual outcomes.11

Monofocal Correction

Most patients who choose monofocal implants will choose best distance correction. Those who have chosen near vision correction in the past have often regretted it due to the limitation in their range of focus. Monofocal IOL options include spherical, aspheric, and toric optics. Spherical IOLs have a constant curve from the center of the lens optic to the periphery, but the power is variable across the lens. This creates positive spherical aberration.11 Aspheric IOLs are made with variable curvatures from edge to edge of the lens, creating stable power across the IOL and reducing spherical aberration.11

Toric IOLs should be considered for eyes in which corneal astigmatism is greater than 0.75 D. Approximately 15% to 20% of patients requiring cataract surgery present with more than 1.50 D of astigmatism.11

Monovision

Monovision is not a recommendation I often make to my patients, unless they have already worn monovision contact lenses successfully. The benefits of monovision include having vision for both distance and near—usually distance in the dominant eye and near in the nondominant. The limitations of monovision include a lack of binocular vision, lack of intermediate vision for computer use, reduced stereoacuity, and reduced contrast sensitivity.

Monovision is occasionally recommended by surgeons or their staff members. If a surgeon recommends monovision to one of my patients, I always suggest a contact lens trial before surgery if the patient has never experienced it. Monovision is not tolerated surgically by approximately 10% to 20% of patients.11

Multifocal

For me, improvements in multifocal IOL technologies have taken the fear out of recommending these premium IOLs to my patients. Patient selection is still important, and setting realistic expectations is key. Patients who are successful multifocal contact lenses wearers especially deserve a discussion of these IOLs.

Simultaneous vision is the concept behind the design of multifocal IOLs. Diffractive multifocals use the Huygens-Fresnel principle. Echelettes, or small steps, on the IOL surface act as a diffraction grating, creating multiple foci through constructive and deconstructive interference of incident light.12 Refractive IOLs use concentric rings of differing powers to achieve the same effect.12 Contrast sensitivity, halos, and glare are often issues with these lenses.

Apodization is a process in which both the diffractive and refractive approaches are combined, resulting in improved image quality and reduced halos and glare. The appropriate amount of light is distributed to near and distant focal points regardless of the lighting situation. This is achieved by contouring the edges of the multifocal zones.13,14 A combination of apodized lens technology with asphericity was used in the development of the Tecnis Symfony (Johnson & Johnson Vision).14

Accommodating IOLs are another type of presbyopia-correcting IOL technology, designed to mimic the accommodation actions of the natural lens. This is accomplished by changing the shape of the lens in the eye or changing its position within the eye in response to contractions of the ciliary muscle.13,14 The Crystalens AO (Bausch + Lomb) is a single-optic IOL with flexible hinged haptics that move the implant as the ciliary muscle contracts.13

FOLLOW-UP

Our final point of discussion with cataract surgery candidates is the postoperative follow-up schedule. Follow-up visits are recommended at 1 day, 1 week, and 1 month after an uncomplicated cataract surgery. OCT evaluations are also conducted at postoperative visits to ensure that no macular edema is present.

Optometrists have the ability and the responsibility to guide their patients through this process. Some optometrists even offer to be with their patients on their day of surgery. When we go above and beyond for our patients, we provide a level of care that no other health care provider is able to offer. Go beyond, and give your patients your best. They deserve it.

1. Calnan-Holt K. Cataract comanagement: the OD ‘point guard.’ Review of Optometry. March 15, 2013.

2. Sutton G, Bali SJ, Hodge C. Femtosecond cataract surgery: transitioning to laser cataract. Curr Opin Ophthalmol. 2013;24(1):3-8.

3. Prickett AL, Bui K, Hallak J, et al. Cyclotorsional and non-cyclotorsional components of eye rotation observed from sitting to supine position. Br J Ophthalmol. 2015;99:49-53.

4. Ianchulev T, Hoffer KJ, Yoo SH, et al. Intraoperative refractive biometry for predicting intraocular lens power calculation after prior myopic refractive surgery. Ophthalmology. 2014;121:56-60.

5. Schweitzer J. The evolution of cataract surgery. Review of Optometry. December 15, 2016.

6. Bethke W. Corneal topography for the cataract surgeon. Review of Ophthalmology. January 24, 2008.

7. Peral A, Alonso J, García-García C, et al. Importance of lid hygiene before ocular surgery: qualitative and quantitative analysis of eyelid and conjunctiva microbiota. Eye Contact Lens. 2016;42(6):366-370.

8. Afsharkhamseh N, Movahedan A, Motahari H, et al. Cataract surgery in patients with ocular surface disease: an update in clinical diagnosis and treatment. Saudi J Ophthalmol. 2014;28(3):164-167.

9. Donnenfeld E, Solomon R, Roberts CW, et al. Cyclosporine 0.05% to improve visual outcomes after multifocal intraocular lens implantation. J Refract Surg. 2010;36(7):1095-1000.

10. Stephenson M. The relationship between dry eye and cataract surgery. Review of Ophthalmology. November 21, 2007.

11. Bhogal-Bhamra GK. Intraocular Lenses, Part 1 - A Review. Optometry Today. January 1, 2017.

12. Bhogal-Bhamra GK. Intraocular Lenses, Part 2 - A Review. Optometry Today. January 1, 2017.

13. Gebhart F. New IOL offers full-distance, good intermediate distance. Ophthalmology Times. July 18, 2017.

14. Gentile RC, Nesmith B, Rosenthal KJ, et al. 6 major advances in ophthalmology: a look back at 2016. Medscape. January 6, 2017.

Shalu Pal, OD, FAAO
• owner, Dr. Shalu Pal, Optometrist, Toronto, Ontario
• financial disclosure: none relevant
• 416-924-9210; @drshalupal; shalupal@live.com