A study in Scientific Reports has analyzed how the characteristics of cataract patients have shifted over the last decade. The research pinpoints trends that could influence how cataract surgery is performed and how intraocular lenses (IOLs) are designed and selected.

Background on Cataract Trends

Cataracts remain a notable global health issue and a primary cause of blindness. As the world’s population continues to age, the number of individuals affected by cataracts is expected to increase substantially.

This means that more cataract surgery patients have a history of high myopia (nearsightedness) and prior refractive surgery to correct vision problems.

• Refractive surgery alters the structure of the eye,which necessitates adjustments in the calculations used to determine the appropriate IOL power.

Prior Research

The research team had previously conducted a similar study, focusing on patients aged 50+ who underwent cataract surgery at the same medical centre between November 2011 and August 2014.

• That earlier study marked the first hospital-based examination of ocular biometrics in cataract patients aged 50 and older in western China.

The key finding was a high prevalence of severe axial myopia, with 13.66% of patients having an axial length (AL) > 26.5 mm. The researchers emphasized the need for further investigation into this phenomenon.

About the Current Study

In this new retrospective study, researchers examined clinicodemographic and ocular biometric data obtained via swept-source optical coherence tomography (SS-OCT) from 25,192 eyes of 25,192 patients aged 40+ who underwent cataract surgery.

The data was collected between 2020 and 2023 at West China Hospital of Sichuan University in Chengdu, China.

Key Findings

The study revealed that as patient age increased,several ocular characteristics tended to decrease:

• Axial Length (AL)
• Anterior Chamber Depth (ACD)
• Aqueous Depth (AQD)
• White-to-White (WTW) measurement

Conversely,corneal refractive power and lens thickness tended to increase with age.

The researchers also identified trends in patients who had undergone refractive surgery,including:

• Deeper ACD
• Deeper AQD
• Thinner lenses
• Longer WTW

“Our analysis of anterior / posterior (A / P) ratio in this cohort was consistent with the fact that PRK and LASIK increase the curvature radio of the anterior corneal surface much more than the curvature radius of the posterior surface,”

More Details from the Research

Of the patients studied,19.66% had axial lengths > 26 mm, and 1.72% had a history of refractive surgery. The incidence of refractive surgery increased from 2020 to 2023, rising from 1.31% to 1.99%.

Among those who had refractive surgery, the most common procedures were laser-assisted in situ keratomileusis (LASIK, 46.23%) and photorefractive keratectomy (PRK, 31.60%).

Patients with a history of refractive surgery were, on average, 12 years younger than those without such a history.

• A larger proportion of thes individuals had axial lengths > 26 mm or corneal refractive power below 38 diopters (D).

Expert Perspective

According to the study authors, “Our analysis of anterior / posterior (A / P) ratio in this cohort was consistent with the fact that PRK and LASIK increase the curvature radio of the anterior corneal surface much more than the curvature radius of the posterior surface.”

This means that clinicians need to consider the impact of prior refractive surgery to ensure accurate IOL calculations.

Study Limitations

The study’s limitations include:

• The patient population was drawn from a large geographic area in southwest China, which may not fully represent other populations in China or worldwide.
• The age inclusion criteria differed between the two studies conducted by the research team (≥ 40 years in the 2020s cohort vs. ≥ 50 years in the 2010s cohort), so comparisons should be made cautiously.

Conclusion

The study indicates that the prevalence of high myopia and prior refractive surgery among cataract patients increased between the 2010s and the 2020s.

• During this period,the age of cataract patients at the time of surgery decreased.

The study authors suggest that these shifts in ocular and demographic characteristics may require updates in:

• Preparations before cataract surgery
• Procedures during surgery
• Post-operative management
• IOL design and selection