Index
It is a type of eye surgery in which an incision is made in the eye’s lens capsule.
In modern cataract operations, the lens capsule is usually not removed.
A posterior capsulotomy is laser surgery that you may need sometime after cataract surgery. It helps you see clearly if your vision becomes cloudy again.
The most common forms of cataract surgery remove almost all crystalline lenses but do not remove the lens capsule (the lens’s outer “bag” layer).
The lens capsule is retained and used to contain and place the artificial, clear intraocular lens implant (IOL). The intraocular lens is held in place in the eye’s natural lens capsule.
Months or years after cataract surgery, the lens capsule may become cloudy in about 30% of the eyes. This is called posterior capsule opacification (PCO).
It is also sometimes called “secondary cataract” or “scar tissue.” With posterior capsulotomy, a laser is used to make an opening in the cloudy capsule. This allows the light to pass through again for a clear view.
Before the advent of laser surgery, a small knife called a cystotome was used to make a hole in the center of the lens capsule, thus providing a clear path for light to reach the retina.
This procedure reduces the clouding of the lens of the eye. This method has been replaced by Nd-YAG laser capsulotomy.
What happens during a posterior capsulotomy?
The procedure is done in your ophthalmologist’s office. It only takes about 5 minutes. This is what will happen:
- Your eye will be numbed with eye drops.
- Your ophthalmologist will point a special laser at the back of the lens capsule and make a small opening.
After the procedure, you can usually do all of your normal daily activities, including driving. Your ophthalmologist will tell you if there are things you should not do right after surgery.
You may need to use an eye drop medicine for a week after surgery. Your ophthalmologist will inform you if necessary.
If you have no other eye problems that affect your vision, your vision should improve in about 24 hours.
What are the risks of posterior capsulotomy?
There are potential risks and complications with posterior capsulotomy, as with any surgery. Here are some of them:
You may have a detached retina (where the tissue lifts from the back of your eye). You can see what looks like a gray curtain moving across your field of vision. You can also see a large number of floats.
The pressure in your eye can increase. The intraocular lens could move through the opening of the posterior capsule. You may have eye swelling, and you may need steroid drops.
Incidence studies of capsulotomy
Posterior capsule opacification is the most common complication after cataract surgery.
It can occur between a few months and many years after intraocular lens implantation, with incidence figures ranging from <5% to 50%.
Neodymium-doped yttrium garnet (Nd: YAG) laser capsulotomy is a widely accepted surgical method to treat posterior capsule opacification, but it is expensive and may risk complications.
Therefore, during cataract surgery, measures are generally taken to prevent or delay the onset of posterior capsule opacification.
Currently, among other strategies, there is great interest from surgeons, patients, and payers in preventing posterior capsule opacification and subsequent Nd: YAG capsulotomy through improvements in intraocular lens material and design.
While there are known risk factors such as rounded edge and sharp edge, more research is needed to understand the role of intraocular lens material and design features in the formation of posterior capsule opacification.
Controlled prospective studies on the incidence of Nd: YAG capsulotomy and posterior capsule opacification by type of intraocular lens have been conducted in the last two decades, reporting more favorable results for hydrophobic acrylic versus hydrophilic intraocular lenses.
Furthermore, the optical diameter of 6 mm intraocular lenses and the sharp optical edge have been shown to reduce the development of posterior capsule opacification in randomized clinical trials (RCTs).
Additionally, favorable results were reported in randomized clinical trials supporting the use of AcrySof bioadhesive material (Alcon Laboratories, Inc., Texas, USA) versus other intraocular lens materials.
Although randomized clinical trials are generally considered the gold standard for evaluating comparative effectiveness, it is usually not feasible to provide estimates in large populations or over extended time horizons.
Similarly, prospective studies post-patient for years or even an outcome of interest may be limited in terms of time and associated cost.
Real-World Evidence (RWE) studies using high-quality databases can capture information from medical records to longitudinally assess long-term outcomes for large cohorts of patients.
Thus providing solid evidence based on actual-world clinical practice. Regulatory bodies such as:
- The U.S. Food and Drug Administration (USFDA) and health technology assessment bodies such as the National Institute for Health and Care for Excellence (NICE) ) from the United Kingdom.
They are increasingly using real-world evidence to support decision-making about medical devices.
Although previously evaluated in prospective, single-center, short duration, and limited sample size clinical studies, the robust, longitudinal evidence for the association between intraocular lens material and Nd: YAG capsulotomy for treating posterior capsule opacification remains. Limited.
The studies aim to evaluate the long-term incidence of Nd: YAG capsulotomy and posterior capsule opacification after age-related cataract surgery.
I compared the 3-year results for hydrophobic acrylic intraocular lenses versus cohorts of other hydrophilic and hydrophobic acrylic monofocal intraocular lenses.
Methods
Data source
Data were collected from 7 U.K. National Health Service (NHS) cataract clinics using Medisoft’s Ophthalmology Electronic Medical Record (EMR) system.
Medisoft has covered ophthalmic care episodes and diagnostic information for> 1 million patients in more than 150 UK ophthalmology clinics.
It is a widely accepted and validated research data source with a strong portfolio of publications, including numerous real-world evidence studies conducted by the Royal College of Ophthalmologists.
All patient data used in this study was completely anonymous and complied with the U.K. National Health Service rules governing the use of healthcare data at the patient level (as defined in the Data Protection Act 1998).
Each approved this study of the Caldicott Guardians of the participating center of the National Health Service.
The sites were selected to provide many procedures, reliable cataract surgery records, and postoperative follow-up data, including the Nd: YAG capsulotomy record in Medisoft’s electronic medical record system.
Each clinic was interviewed to ensure that all follow-up appointments for the diagnosis of posterior capsular opacification / YAG capsulotomy were recorded only at the center where cataract surgery was performed.
Study population
Eye-level data recorded between January 1, 2010, and December 31, 2016, were extracted for all eyes undergoing cataract surgery at selected clinics, with details recorded of the type of intraocular lens implanted.
After data extraction, all eyes implanted with monofocal acrylic intraocular lenses were included in the study.
To avoid confusing the study, cohorts with eyes implanted with non-acrylic intraocular lenses or with models of intraocular lenses embedded on rare occasions.
Intraocular lenses used in less than 100 cases in all clinics, multifocal or toric intraocular lenses, were excluded.
To be included in the study, the eyes were required to have the first registration of phacoemulsification of the lens and bag implantation of a monofocal acrylic intraocular lens between January 1, 2010, and December 31, 2013.
Ensure at least three years of follow-up data were available in the Medisoft database.
This date of cataract surgery and intraocular lens implantation was defined as the index date.
Data from patients who died within the follow-up period and whose death record was present in the Medisoft database were excluded.
As the data used for the study originated from visits by specialists in ophthalmology centers, it was assumed that:
- If a patient was not recorded as deceased and was not seen at the clinic after the index date, the patient did not experience the outcomes of interest (Nd: YAG capsulotomy or posterior capsular opacification).
- The selected clinics confirmed that they were the only units in their geographic area that performed Nd: YAG capsulotomies. All registered the procedure in the Medisoft system, minimizing the probability of loss to follow-up due to transfer to other centers.
However, it is possible that some patients relocated after cataract surgery, and their postoperative medical history was lost to follow-up.
In attempts to exclude secondary non-age-related cataract types, the eyes of patients younger than 65 years at the date of cataract surgery were not included in the analyzes.
Furthermore, eyes were excluded if:
- They had invalid cataract surgery records (for example, more than one record for the same look) or if they had a history of joint surgeries or complications before, after, or during cataract surgery (as defined by clinical information).
Statistic analysis
All analyzes were performed at eye level using Statistical Analysis Software (SAS) version 9.4.
The selected eyes were categorized as 1 of 3 different study cohorts according to the optical material and water properties of the implanted acrylic intraocular lenses:
AcrySof intraocular lenses are hydrophobic; water-repellent non-acrylic acrylic intraocular lenses; and hydrophilic intraocular lenses other than AcrySof.
For each cohort, records of the Nd: YAG capsulotomy procedure and posterior capsule opacification were used to assess incidence ratios and 95% confidence intervals (CI) for three years from the index date.
Results were also reported in shorter time intervals of 1 and 2 years. Nd: YAG capsulotomy was identified in real-world evidence based on:
The Classification of Interventions and Procedures of the Office of Population Classification and Census of the National Health Service, version 4 (OPCS-4), using the codes C73.3 (capsulotomy of the posterior lens capsule) and Y08. 6 (YAG posterior capsulotomy).
The presence of opacification of the posterior capsule was identified within the records of postoperative complications of cataract surgery.
For the incidence of Nd: YAG capsulotomy, the descriptive survival curves during the three years were plotted using the Kaplan-Meier method, so the failure event was a record of the Nd: YAG capsulotomy procedure.
In addition, adjusted and unadjusted odds ratios (OR) (using a stepwise approach) and 95% confidence intervals for Nd: YAG capsulotomy at the 3-year follow-up period were calculated using multivariate logistic regression for patients, not acrylics.
For non-acrylic and acrylic hydrophobic acrylic cohorts other than AcrySof vs. AcrySof IOL cohort includes both multi-piece and single-piece IOLs. The level of significance adopted was 0.05.
Intraocular lenses of different haptic designs may not produce the same clinical results.
Nd: YAG capsulotomy incidence ratios and odds ratios were also analyzed for the largest subgroup of eyes implanted with one-piece acrylic intraocular lenses (92% of the total across the three intraocular lenses).
Discussion
The current study found that approximately one-tenth of cases develop posterior capsule opacification within three years after cataract surgery. More than half of them require an Nd: YAG capsulotomy procedure to treat capsule opacification. Later.
The study demonstrated that the intraocular lens material and its surface properties could influence the incidence of Nd: YAG capsulotomy and posterior capsule opacification in acrylic intraocular lenses.
The results confirmed earlier evidence from smaller prospective studies that the incidence ratios of Nd: YAG capsulotomy and posterior capsule opacification are lower for hydrophobic acrylic IOLs compared to hydrophilic acrylics.
The study further found that three years after implantation, AcrySof IOLs are associated with:
- There is a significantly lower risk of requiring an Nd: YAG capsulotomy and has the lowest incidence of posterior capsule opacification compared to cohorts of other hydrophilic and hydrophobic acrylic intraocular lenses.
This protective effect was independent of potential confounders and was confirmed when the analysis was performed on the largest subgroup of one-piece intraocular lenses.
Similar trends were found in a recent 900-eye actual Swedish evidence study that showed that compared to a hydrophobic acrylic intraocular lens with a sharp posterior optic edge, a hydrophilic acrylic intraocular lens was associated with twice as many Nd: YAG capsulotomies in one five years.
Another study that followed 1,527 patients for 3.5 years also confirmed that the risk of Nd: YAG capsulotomy and posterior capsule opacification was significantly higher in hydrophilic intraocular lenses compared to hydrophobic intraocular lenses.
This study is the most extensive analysis of the incidence of Nd: YAG capsulotomy and posterior capsule opacification performed to date.
It has been shown that different lens designs can also impact the development of posterior capsule opacification after implantation.
One-piece acrylic IOLs result in more Nd: YAG capsulotomies and posterior capsule opacification than multi-piece acrylic IOLs.
To evaluate the effect of intraocular lens materials without the confounding factor of haptic designs, analyzes were performed on the subgroup of eyes implanted with one-piece intraocular lenses (the most common type of intraocular lens used in our sample).
This subgroup analysis confirmed that Acrysof one-piece intraocular lenses are associated with a significantly lower risk of Nd: YAG capsulotomy and the incidence of posterior capsule opacification versus others.
Studying real-world longitudinal data from over 50,000 procedures performed at seven different sites across the U.K., with the implantation of various intraocular lenses, provides a robust data set.
It offers evidence from actual clinical practice beyond randomized clinical trials conducted in a controlled environment.
Baseline characteristics were assessed to reduce biases associated with non-randomization, and statistical adjustment was performed for potential confounders.
Possible concerns about the reliability of Nd: YAG capsulotomy rates in retrospective real-world studies compared to randomized clinical trials were also explained.
To avoid the potential bias, patients did not return to the same clinic to diagnose posterior capsular opacity and treatment with Nd: YAG.
It was confirmed with all participating sites that each clinic would routinely perform its Nd: YAG capsulotomy procedures and would not have any other local health service units that routinely perform Nd: YAG capsulotomy on their patients.
Another concern could be that differences in practice between clinics could affect Nd: YAG capsulotomy and posterior capsular opacity rates.
The data did not contain information on the exact level of experience of each surgeon, size of capsulorhexis, or location relative to the optic or type of initial cataract.
This study represents a considerable sample size of patients across multiple clinics and therefore reflects real-world treatment practice, which is naturally variable instead of clinical trials.
Therefore, it was assumed that these factors were evenly distributed among the three groups.
An attempt was made to control the site by including a site identification variable in the logistic regression model.
However, due to the high correlation between lens type and site identification (sites generally wear one or two lenses), site identification was not included in the final model to avoid collinearity.
Removing the site identification from the model did not substantially change the final results.
Many studies on Nd: YAG capsulotomy and posterior capsular opacity rates have compared intraocular lens material and designs, showing that a sharp square edge of the intraocular lens is associated with lower rear capsular opacity rates.
Different intraocular lenses are believed to have other properties at the square edges. This could be related to the intraocular lens material that may explain the different posterior capsular opacity rates observed in this study.
However, the effect of other properties inherent in the AcrySof intraocular lens or its material that contribute to a lower incidence of posterior capsular opacity cannot be excluded.
It was not possible to analyze the effect of intraocular lens configuration and rim morphology on the incidence of Nd: YAG capsulotomy and posterior capsular opacity within different intraocular lens cohorts.
Despite this, AcrySof IOLs with an uninterrupted square edge (360 °) and one-piece design have been shown to have a lower incidence of posterior capsular opacity.
And a significantly lower risk of undergoing an Nd: YAG capsulotomy procedure than acrylic hydrophilic and hydrophobic IOL with a 360 ° square (continuous) edge.
This finding contrasts with studies evaluating patients who had a non-AcrySof intraocular lens implant with a continuous optic edge in 1 eye and an AcrySof intraocular lens with an interrupted visual sharpness in the other eye.
There were no different statistical data on the incidence of posterior capsular opacity between the two types of intraocular lenses.
Nixon et al. reported a significantly lower incidence of posterior capsular opacity in eyes implanted with a continuous 360 ° square border.
The small sample size of these studies and other factors, such as lens models and the short follow-up duration, may explain the findings’ discrepancies.
Although evaluating other possible risk factors associated with posterior capsular opacity was not the objective of this study, adjusted multivariate analysis showed that some characteristics are independently associated with a higher probability of undergoing Nd: YAG capsulotomy.
These include the presence of complications after surgery, a history of pathology (for example, glaucoma, age-related macular degeneration, diabetic retinopathy), and, to a lesser extent, female gender and younger age, which is consistent with the evidence. Published.
However, it is essential to remember that our study restricted the age to 65 years or older, so our results are limited to patients in this age cohort only.
It was also found that eyes implanted with lower power intraocular lenses were marginally but significantly associated with an increased risk of Nd: YAG capsulotomies, which may be related to increased myopia and axial length of the eye.
However, a previous study found that axial myopia did not significantly increase the area or incidence of capsular opacity after four years, although the study had a much smaller sample size than this analysis.
Another possible explanation for this association could be a change in the shape of the square edge of the intraocular lens.
Finally, the authors could not find a clear explanation for the lower odds ratios recorded for the eyes with better higher corrected distance visual acuity or those operated by older learners compared to the consultants.
Future analyses should investigate in more detail the possible ocular factors associated with the development of posterior capsular opacity regardless of the properties of the intraocular lens.
The main strengths of this study are the longitudinal design and the large sample size, which allowed reliable statistical power in comparative analyzes and for the selection of a representative cohort of patients.
The median age for cataract surgery and the gender distribution in our study population were comparable to those reported in the National Ophthalmology Database (NOD) Annual Audit Report 2016.
Other essential strengths of the current analysis include the integrity of data collection and consistency of recording across clinics, which is a requirement of Medisoft’s electronic medical record program.
This allowed us to collect a reliable set of parameters from multiple sites, allowing adjustment for potential confounders in the regression model.
Finally, although retrospective studies may be limited by incomplete data collection and loss of patients to subsequent Nd: YAG capsulotomy.
Data loss was minimized by including only clinics with no alternative local pathways for patients who received the Nd: YAG capsulotomy procedure posterior capsular opacity.
Despite these strengths, the authors acknowledge some limitations to the study.
Medisoft data only contains partial access to primary care data, limiting information on the patient’s complete medical history. Similarly, death may have been underreported.
However, it is believed that this will apply equally to all comparative cohorts and, therefore, will not significantly impact the findings.
Finally, a panel of clinics with high-quality Medisoft data entry is selected for cataract surgery and Nd: YAG capsulotomy, which may have biased the results.
To mitigate these biases, clinics with complete information on the medical history are selected.
According to the results of this study, in the three years after cataract surgery, the risk of undergoing an Nd: YAG capsulotomy and the incidence of posterior capsular opacity are significantly lower when using AcrySof intraocular lenses.
Compared to other hydrophobic and hydrophilic acrylic intraocular lens cohorts.
The prevention of posterior capsular opacity is clinically essential and beneficial for patients. This condition is associated with reduced visual performance and significant morbidity in the older age group that this study analyzed.
Poor vision is associated with depression, falls, and reduced mobility in this age cohort.
Additionally, reducing the requirement for Nd: YAG capsulotomy to correct posterior capsular opacity can reduce healthcare costs and associated clinical risks.
Prevention of posterior capsular opacity and subsequent Nd: YAG capsulotomies may:
