Introduction

A cataract is a vision-hampering disease resulting from the gradual cloudiness and thickening of the natural lens of the eye. A cataract is the leading cause of reversible blindness in the world. Its definitive treatment is lens extraction and placement of an intraocular lens implant. Various methods are utilized to extract the intraocular lens e.g intracapsular extraction, extracapsular extraction, or phacoemulsification, the latter of which is most commonly used.

Placement of multifocal intraocular lenses during cataract surgery allows patients to gain distance and near vision, but careful selection of patients is critical and depends on multiple factors. Not all patients are candidates for multifocal lenses. 

Multifocal Lens Implant

Traditional monofocal lenses give patients either good distance or good near vision, but not both. Multifocal lens implants are a manifestation of modern technology to meet the expectations of patients and improve both distance and near vision. They do so by dividing light into different focal points and providing better visual quality. However, careful selection of the patient and type of lens is critical to the success of multifocal lens implants.

Multifocal lenses may use refraction of light, diffraction, or both to help in focusing objects on the retina. Therefore, they are categorized into the following:

Refractive IOLs

• The refractive lens implants create multifocal focal points and usually provide far & intermediate vision. However, they have limited near vision.
• They depend on the dynamics/size of pupils.
• They may cause halos and glare.
• Sometimes, they are designed with a changing curvature to provide vision across all distances.

Diffractive IOLs

• They are formed by diffractive microstructures in concentric zones.
• Generally, they provide good far and near vision.
• Intermediate vision may be limited.
• They also depend on the pupil dynamics/size. 
• Lower incidence of glare and halos than refractive IOLs.

Trifocal IOLs

• Provide distance, near and intermediate vision.
• They may cause glare and halos. 

Traditional Intraocular Lenses

They are also known as mono-focal lenses. They are least expensive and provide only fixed vision e.g far, near, or intermediate. The drawback of these intraocular implants is the necessary use of glasses. Patients with astigmatism will have to wear glasses all the time after cataract surgery for the sharpest vision.

Outcomes Of Multifocal Lens Implants

Patient satisfaction depends on identifying vision requirements and expectations, having strong knowledge of IOL designs, potential complications, and their management. Studies show a very high level of satisfaction in general. The trifocal IOLs perform better for patients who desire intermediate vision.

Advanced multifocal lens implants are available now with an expanded depth of focus. The new technologies are being utilized to enhance the vision range with fewer complications.

Complications Of Multifocal Lens Implants

The following are the main factors behind the dissatisfaction of the patient with intraocular lens implants:

Residual refractive error

• Multifocal lens implants are sensitive to residual refractive error and lead to patient dissatisfaction.
• It happens due to inadequate biometric analysis, inadequate selection of IOL power, and errors in IOL position.
• Photorefractive keratectomy enhancements after the surgery prove beneficial. Sometimes intraocular lenses need to be replaced.

Posterior capsular opacification

• It is the most common cause of blurred vision with multifocal lens implants.
• Hydrogel IOLs, rounded IOLs, and larger capsular openings are associated with a high incidence of posterior capsular opacification.
• This can be resolved with a short in-office laser procedure.

Dry eye

• Dry eye is due to tear film insufficiency leading to discomfort and blurred vision.
• Dry eye can worsen after surgery and may lead to blurred vision and glare.
• It is important to treat dry eye before and after surgery, especially when considering a multifocal lens. 

Displacement of the intraocular implant

• Rarely a misalignment of the intraocular lens can occur and may affect the vision.

Inadequate pupil size

• Pupil size determines which multifocal intraocular lens will be used.
• Patients with small pupil sizes may notice poorer near vision. Patients with large postoperative pupil sizes may complain about the increased photopic phenomenon (glare, halos, etc).

Conclusion

Multifocal lenses often allow patients to be glasses free and generally have a very high level of patient satisfaction, but not every patient is a candidate for multifocal lens implants. Their visual needs should be understood completely before surgery.

Your ophthalmologist will conduct an extensive preoperative evaluation to determine the right intraocular lens for you. Talk to them about your options today!

References

1. Ocampo, V. V. D., Jr MD. (2021, July 29). Senile Cataract (Age-Related Cataract): Practice Essentials, Background, Pathophysiology. Medscape. https://emedicine.medscape.com/article/1210914-overview
2. Multifocal intraocular lenses: Types, outcomes, complications and how to solve them. (n.d.). PubMed Central (PMC). Retrieved September 16, 2021, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5747227/
3. E. (2014, June 11). Different Types of IOLs. Your Sight Matters. https://yoursightmatters.com/different-types-iols/
4. Optimizing outcomes with toric intraocular lenses. (2017, December 1). PubMed Central (PMC). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5742958/

Author

Eye Surgeons Associates Drs. Meiraj A. Siddiqui, Zuhair H. Peracha, Manal H. Peracha-Riyaz, Eric Zuckerman and Leila Siblani are dedicated to excellence in eye care and service. We utilize the latest treatment methods and procedures, including routine eye care, cataract surgery, glaucoma treatment, retinal disease management, diabetic eye treatment, and eyelid surgery.