CATARACT SURGERY & ASTIGMATISM: What You Need to Know

Cataracts and astigmatism are common ocular conditions that can significantly impair vision. Cataracts involve the clouding of the eye’s natural lens, leading to reduced visual acuity. Meanwhile, astigmatism, a refractive error, results from an irregular curvature of the cornea or lens, causing blurred or distorted vision at all distances. These conditions frequently coexist, especially in older adults, due to the natural ageing process. Modern cataract surgery can address both conditions simultaneously, potentially reducing dependence on corrective eyeglasses.

Our blog article will examine the relationship between cataracts and astigmatism, detail surgical correction methods, and discuss surgical trends, outcomes, and other healthcare considerations. The increasing global life expectancy suggests that the co-occurrence of these conditions will likely become a more significant public health concern.

Meet our Medical Director: Dr Lim Wei Kheong Jimmy

MBBS, MMed (Ophth), MRCSEd (Ophth), FRCSEd (Ophth), FAMS

How Cataracts Influence Astigmatism

A cataract is the clouding of the eye’s natural lens, obstructing light passage to the retina and decreasing vision. Ageing is the primary cause, involving the breakdown and clumping of lens proteins. Other contributing factors include eye trauma, radiation exposure, genetic predisposition, diabetes, smoking, and prolonged sunlight exposure. Symptoms include blurred or cloudy vision, faded colours, light sensitivity and glare, night vision difficulties, frequent prescription changes, and double vision.

Astigmatism, on the other hand, is a common refractive error characterised by a rotational asymmetry in the eye’s refractive power. This irregularity, typically in the cornea (corneal astigmatism) or sometimes the lens (lenticular astigmatism), causes light rays to focus at multiple points on the retina instead of a single point, resulting in blurred or distorted vision at all distances. Symptoms include blurred or distorted vision, eyestrain, headaches, night vision difficulties, and squinting.

Cataracts can influence the presence or severity of astigmatism by affecting the shape and structure of the eye’s lens. As cataracts progress, the natural lens becomes denser and less flexible, altering light refraction and potentially worsening pre-existing astigmatism. The thickening of the lens can also cause positional shifts, further contributing to changes in the degree and axis of astigmatism. These changes can exacerbate visual disturbances for individuals with both conditions.

What is Cataract Surgery

Cataract surgery is a common and increasingly prevalent procedure in Singapore. Approximately 25,000 to 30,000 cataract surgeries are performed annually in the country. The Singapore National Eye Centre (SNEC) performs around 17,000 cataract surgeries each year. Historical data from 1991 to 1996 showed an average rate of 356.4 cataract operations per 100,000 persons per year in Singapore.

Cataract surgery, by removing the clouded natural lens and replacing it with an artificial intraocular lens (IOL), addresses lenticular astigmatism. However, pre-existing corneal astigmatism will not be corrected by standard cataract surgery alone and may appear to worsen if not specifically addressed during the procedure. Therefore, a comprehensive approach involves removing the cataract and correcting the coexisting corneal astigmatism.

Ongoing advancements in surgical technologies and lens designs continue to refine cataract surgery methods, offering increasingly effective solutions.

Continually Advancing Technology

Advanced diagnostic technologies are pivotal in pre-operative assessment. For one, Corneal Topography and Tomography, imaging techniques that provide detailed maps of the cornea’s curvature and thickness, are responsible for characterising the type and extent of astigmatism.

Another test, the Optical Biometry, is a non-invasive method that measures the eye’s axial length, corneal curvature, and anterior chamber depth, essential for IOL power calculation. Using Wavefront Analysis, your doctor assesses the eye’s entire optical system, identifying higher-order aberrations that may contribute to visual disturbances. It can assist in selecting the most appropriate IOL and surgical strategy.

Emerging technologies and research are driving advancements in astigmatism correction during cataract surgery. Toric intraocular lenses (IOLs) play a crucial role, specifically designed to correct astigmatism by compensating for the cornea’s irregular shape. These lenses are precisely calculated and placed during cataract surgery to reduce or eliminate astigmatism, leading to improved uncorrected visual acuity. The accuracy of pre-operative measurements and precise surgical implantation are paramount for optimal outcomes with toric IOLs. 

Managing Risks & Expectations

Patients undergoing cataract surgery with astigmatism correction in Singapore can generally expect significant improvements in their vision and a reduced need for glasses or contact lenses. Many patients experience a significant reduction or even elimination of their dependence on glasses, particularly for distance vision. Studies show that patients are often highly satisfied with their vision, post-surgery.  

Even with the advancements in astigmatism correction techniques, potential complications can still arise during and after surgery. Intraoperative risks include incorrect positioning of IOLs. To minimise these risks, preoperative planning on your surgeon’s part is key. Patients should not miss their regular post-operative appointments, which are essential to address any potential complications.

Managing your expectations is no less. While surgery can significantly improve vision, complete spectacle independence is not guaranteed for all patients. Additionally, while the recovery period is typically short, with most patients experiencing improved vision within days, outcomes may vary. Complete stabilisation of vision may take several weeks.

JL Eye Specialists for Cataract Surgery in Singapore

JL Eye Specialists offers cataract surgery founded on the experience of our Medical Director Dr. Lim Wei Kheong Jimmy. He has served over two decades as a senior consultant at the National Healthcare Group Eye Institute. His training includes fellowships at Baylor College of Medicine in the USA and IROC in Switzerland, where he studied under experienced ophthalmologists.

Dr. Lim’s areas of focus include cataract surgery and LASIK, and he is involved in research, which has led to publications in peer-reviewed journals. Dr. Lim participates in training junior ophthalmologists and serves as a postgraduate examiner. His contributions have been acknowledged, including the Baylor College of Medicine Fellow Teaching Award. Dr. Lim has also been invited to share his experience at regional and international conferences. 

Please contact us at 6258-8966 to schedule a consultation, and Dr. Lim will be glad to answer your questions.

REFERENCES:

1. Outcome of our care – Cataract | National University Hospital (NUH), Singapore’s Leading University Hospital 
2. Prevalence of Refractive Errors in a Multiethnic Asian Population: The Singapore Epidemiology of Eye Disease Study | IOVS
3. Prevalence rates and epidemiological risk factors for astigmatism in Singapore school children – PubMed 
4. Prevalence of astigmatism and anisometropia in Chinese residents in Singapore, by age and sex. – ResearchGate 
5. Cataract Surgery – Diagnosis, Procedure & Risks – SingHealth 
6. A PATIENT GUIDE – Singapore National Eye Centre 
7. Consensus on the management of astigmatism in cataract surgery – PMC
8. Correcting Corneal Astigmatism with Corneal Arcuate Incisions during Femtosecond Laser Assisted Cataract Surgery – PMC – PubMed Central
9. Refractive Outcomes after Cataract Surgery – PMC – PubMed Central
10. Cataract & Comprehensive Ophthalmology – Singapore National Eye Centre 
11. Journal of Cataract & Refractive Surgery: Optimizing outcomes with toric intraocular lenses
12. American Academy of Ophthalmology: Astigmatism Correction During Cataract Surgery
13. Journal of Cataract & Refractive Surgery: Femtosecond laser arcuate keratotomy for the correction of residual astigmatism after cataract surgery
14. American Academy of Ophthalmology: Femtosecond Laser Cataract Surgery