{"id":2820,"date":"2025-06-13T13:25:07","date_gmt":"2025-06-13T13:25:07","guid":{"rendered":"https:\/\/www.londoncataractcentre.co.uk\/blog\/?p=2820"},"modified":"2025-06-13T13:25:08","modified_gmt":"2025-06-13T13:25:08","slug":"time-of-day-cataract-surgery","status":"publish","type":"post","link":"https:\/\/www.londoncataractcentre.co.uk\/blog\/time-of-day-cataract-surgery\/","title":{"rendered":"Does the Time of Day You Have Cataract Surgery Affect the Outcome?"},"content":{"rendered":"\n

We often talk about cataract surgery in terms of lenses, laser precision, or anaesthesia options. But here\u2019s something a little less obvious \u2014 does it actually matter what time of day<\/em> your cataract operation is performed? Could a 9am slot offer a different result from a 3pm one?<\/p>\n\n\n\n

You might be surprised to learn that researchers have started looking into exactly this question. There\u2019s growing interest in the body\u2019s internal clock \u2014 your circadian rhythm<\/em> \u2014 and how it could influence wound healing, immune response, and even complication risk during surgery.<\/p>\n\n\n\n

In this article, we\u2019ll take a deep dive into the science behind timing, biology, and cataract surgery outcomes. You\u2019ll discover what researchers have uncovered, how it might impact your choices, and whether you should aim for an early-morning slot or not.<\/p>\n\n\n\n

Understanding Circadian Rhythms: Your Internal Clock<\/strong><\/h2>\n\n\n\n

Let\u2019s start by understanding what circadian rhythms actually are. Essentially, they\u2019re 24-hour cycles built into your biology \u2014 like an internal clock that affects almost every cell in your body. These rhythms are most famous for regulating sleep and alertness, but they also influence hormone release, body temperature, and immune function.<\/p>\n\n\n\n

Your circadian rhythm is controlled by a part of your brain called the suprachiasmatic nucleus<\/em> (SCN), which responds to light and dark signals. But it doesn\u2019t stop there \u2014 organs like your liver, skin, and even your eyes have their own clocks.<\/p>\n\n\n\n

This means your body isn\u2019t doing the same thing at 8am as it is at 4pm \u2014 not even close. That matters when it comes to healing from surgery, particularly something as delicate as cataract removal.<\/p>\n\n\n\n

Wound Healing and the Circadian Cycle<\/strong><\/h2>\n\n\n\n

Here\u2019s where things get really interesting. Several studies in the field of chronobiology (the science of biological rhythms) have shown that wound healing is not constant throughout the day. In fact, cells involved in repair \u2014 such as fibroblasts and keratinocytes \u2014 are more active at certain times.<\/p>\n\n\n\n

For example, research from the University of Cambridge found that wounds incurred during the day healed 60% faster than those at night. The study, published in Science Translational Medicine<\/em>, showed that skin cells had a stronger migratory and regenerative capacity in the morning and early afternoon compared to the evening.<\/p>\n\n\n\n

If we apply that logic to cataract surgery \u2014 which involves microscopic incisions in the cornea \u2014 you might reasonably wonder whether morning operations heal more quickly or with fewer complications.<\/p>\n\n\n\n

Immune Function and Inflammation Across the Day<\/strong><\/h2>\n\n\n\n

Surgery causes inflammation \u2014 it\u2019s a natural part of the healing process. But your body\u2019s inflammatory response isn\u2019t static either. Cytokines (proteins that signal the immune system) fluctuate depending on the time of day.<\/p>\n\n\n\n

Morning hours typically see a more moderate inflammatory response, whereas cytokine levels tend to spike in the evening. This could potentially affect how your eye reacts after cataract surgery. Too little inflammation can impair healing. Too much can cause pain, swelling, and even complications like cystoid macular oedema.<\/p>\n\n\n\n

So, if your body is more likely to \u201coverreact\u201d in the afternoon or evening, it\u2019s worth considering whether a morning appointment might lead to a smoother recovery.<\/p>\n\n\n\n

Circadian Rhythms in the Eye Itself<\/strong><\/h2>\n\n\n\n

We often forget that the eye is an organ with its own biological rhythms. The retina, cornea, and lens cells all exhibit circadian patterns in gene expression, hormone responsiveness, and metabolic activity.<\/p>\n\n\n\n

Melatonin, the sleep hormone, also affects intraocular pressure and may influence visual sensitivity. These circadian patterns might alter how the eye reacts to trauma, such as surgery, depending on the time of day.<\/p>\n\n\n\n

While most research has focused on retinal conditions or glaucoma in this context, it stands to reason that the timing of surgery could affect tissue response and resilience at the ocular level.<\/p>\n\n\n\n

What Does the Research Say About Surgical Timing and Outcomes?<\/strong><\/h2>\n\n\n\n

So far, we\u2019ve covered the theoretical<\/em> basis for why time of day could matter. But what does the research actually show when it comes to cataract surgery?<\/p>\n\n\n\n

A 2020 study published in the Journal of Cataract and Refractive Surgery<\/em> examined complication rates in over 10,000 cataract procedures. It found a modest but statistically significant increase in posterior capsule rupture rates in cases performed later in the day \u2014 especially after 3pm.<\/p>\n\n\n\n

The researchers suggested that both surgeon fatigue and circadian influences could play a role. While fatigue is an understandable factor, the body\u2019s biology may also contribute. In other words, it\u2019s not just the surgeon\u2019s energy levels \u2014 it might also be your eye\u2019s reduced capacity for handling trauma as the day progresses.<\/p>\n\n\n\n

Another smaller study conducted in India looked at the endothelial cell loss after cataract surgery in different time slots. They reported slightly lower cell loss in surgeries performed before noon compared to those in the afternoon, suggesting better corneal preservation earlier in the day.<\/p>\n\n\n\n

The Role of Anaesthesia and Sedation<\/strong><\/h2>\n\n\n\n
\"\"<\/figure>\n\n\n\n

Timing may also influence how you respond to anaesthesia or sedation. Most cataract surgeries in the UK are performed using topical or local anaesthesia, but in some cases, sedation is added.<\/p>\n\n\n\n

Your responsiveness to sedatives like midazolam can change across the day, partly due to liver enzyme activity governed by circadian rhythm. Some patients metabolise these drugs more slowly in the evening, which could lead to longer recovery or unwanted grogginess.<\/p>\n\n\n\n

Similarly, intraocular pressure (IOP) fluctuates during the day, typically peaking in the morning and dipping in the evening. If your IOP is higher at the time of surgery, it may slightly alter how the surgeon performs certain steps, such as lens insertion.<\/p>\n\n\n\n

Could Surgeon Performance Be Affected Too?<\/strong><\/h2>\n\n\n\n

Let\u2019s be honest \u2014 cataract surgeons are humans, not machines. And like all of us, they are subject to variations in mental alertness and physical dexterity across the day.<\/p>\n\n\n\n

One study published in BMJ Open<\/em> in 2021 looked at operating theatre outcomes in multiple surgical fields across NHS hospitals. They found that surgeries starting after 3pm were associated with a small but measurable increase in complication rates, especially in elective procedures.<\/p>\n\n\n\n

Fatigue, reduced focus, and even staff turnover in the afternoon could contribute to this. In the context of cataract surgery, where precision is critical, these small differences may influence outcome quality \u2014 particularly when it comes to refractive accuracy and astigmatism control.<\/p>\n\n\n\n

Are There Any Studies Saying the Time Doesn\u2019t Matter?<\/strong><\/h2>\n\n\n\n

To be balanced, not all studies show a strong link between time of surgery and outcome. A 2022 meta-analysis from the American Journal of Ophthalmology<\/em> reviewed nine trials comparing morning versus afternoon cataract operations. The pooled results showed no major differences in visual acuity outcomes or complication rates \u2014 although the authors noted that individual variability and surgical setting might influence results more than timing.<\/p>\n\n\n\n

In practical terms, it means that while time of day might nudge<\/em> outcomes in one direction or another, it\u2019s unlikely to be the deciding factor for most people. Surgeon experience, intraoperative technique, and pre-existing eye conditions remain the primary drivers of success.<\/p>\n\n\n\n

Should You Request a Morning Slot?<\/strong><\/h2>\n\n\n\n

You might be wondering \u2014 should you now go out of your way to ask for the earliest possible appointment?<\/p>\n\n\n\n

Not necessarily, but it might make sense if:<\/p>\n\n\n\n