JCRS this month
Updated: 11 minutes ago
Concise updates of important studies from JCRS this month
All you need to know about the latest in IOL optics, IOL power calculation, corneal topography and refractive outcomes from peer reviewed papers this month
What is the impact of pupil size on defocus curve attained with diffractive multifocal IOLs?
Davidova P, Kaiser KP, Jandewerth T, et al.Impact of pupil size on defocus curve, contrast sensitivity and patient satisfaction in a diffractive, simultaneous vision intraocular lens.J Cataract Refract Surg. 2026;52(9):843–849.DOI: 10.1097/j.jcrs.0000000000001912.
What did they study?
This was a post-hoc analysis of prospective studies involving 52 patients, mean age 68 years, who had bilateral implantation of the AcrySof IQ PanOptix diffractive simultaneous-vision IOL.
Patients were assessed 3 months after surgery. The investigators measured:
monocular defocus curves
photopic and mesopic pupil size
binocular visual acuity at different distances
contrast sensitivity
spectacle independence
satisfaction with several everyday activities.
Importantly, pupil size was measured objectively using infrared pupillometry.
The pupil-size classification is particularly interesting
They did not simply report an average pupil.
They categorized pupils as:
Condition | Small | Medium | Large |
Mesopic | ≤4 mm | >4–5 mm | >5 mm |
Photopic | ≤2.5 mm | >2.5–4 mm | >4 mm |
The mean measured pupil sizes were:
Mesopic: 4.24 mm, range 2.60–6.10 mm
Photopic: 3.38 mm, range 1.20–5.60 mm.
That ≤2.5 mm photopic threshold is therefore an actual study definition—not an arbitrary cutoff added to the figure.
What happened to the defocus curve?
The investigators found that smaller pupils were associated with better visual acuity across the defocus curve and a larger range of depth of field. However, the relationship wasn't equally strong everywhere. The effect was particularly apparent toward near
Photopic pupil size showed:
a weak correlation with near visual performance
some correlation with the intermediate range
stronger relevance to the range of depth of field.
So the important message isn't simply:
Small pupil = better defocus curve.
It is more accurately:
With this diffractive simultaneous-vision IOL, smaller pupil size was associated particularly with better near performance and a wider useful range of vision.
What is “range of depth of field” in this study?
They evaluated the range of defocus over which visual acuity remained at or better than specified logMAR thresholds, including ≤0.2 and ≤0.3 logMAR.
Pupil size showed a moderate correlation with these ranges under both photopic and mesopic conditions. In practical terms: smaller pupil → the patient could maintain a given level of visual acuity over a wider defocus range.
What about spectacle independence?
This is another clinically relevant finding.
Smaller photopic pupils were associated with greater near spectacle independence.
The effect wasn't reported as a universal improvement in spectacle independence at every distance.
The strongest relationship was specifically with near spectacle independence.
What about patient satisfaction?
Interestingly, the pupil effect was not universal across all activities.
There was a trend toward greater satisfaction with newspaper reading in patients with smaller pupils. But for the other assessed activities, pupil size was not statistically significant according to the abstract.
The optical explanation
This is where the paper becomes particularly interesting for IOL optics.
A smaller pupil means that the eye samples a smaller central portion of the optical system.
That reduces the contribution of peripheral rays and therefore reduces the impact of:
higher-order aberrations
peripheral optical imperfections
defocus-related blur
At the same time, a smaller aperture produces the familiar increase in depth of field.
For a diffractive simultaneous-vision IOL, however, there is another layer: the pupil determines how much of the diffractive optic is actually contributing to the retinal image.
Therefore, the clinical defocus curve is not purely a property of the IOL. It is the result of an interaction: IOL optical design + pupil size + ocular aberrations + retinal/visual factors
The authors' results provide clinical evidence for this interaction. A recent review discussing this study likewise notes that smaller pupils with PanOptix were associated with better visual acuity across the defocus curve and greater depth of field.
END of Sept 2026 update
Does the apply of capsular tension ring (CTR) improve rotational stability in high myopia patients - Evidence from JCRS
Toric IOL Stability: What Determines It?
The following three factors are important in determining the stability of a toric IOL.
First, capsular-bag geometry: This includes the size and shape of the capsular bag. Parameters such as axial length and white-to-white may provide useful clinical clues about the underlying ocular anatomy, although they are indirect biomarkers of capsular-bag dimensions.
Second, zonular support: Zonular laxity can allow the IOL to decenter or rotate. In a toric IOL, this can reduce the effectiveness of astigmatic correction and manifest clinically as residual astigmatism.
Third, the interaction between the IOL and the capsular bag: IOL diameter, haptic design, capsular-bag dimensions, and the way the haptics interact with the capsule can all influence postoperative rotational stability, centration, and tilt.
High axial length may influence all three of these factors—capsular-bag geometry, zonular support, and the IOL–capsular-bag interaction.
What did this study investigate?
This study looked at whether adding a capsular tension ring, or CTR, could improve toric IOL stability in eyes with high axial myopia.
The study included 90 eyes of 68 patients, all with an axial length of at least 26 mm.
The patients received either:
a toric IOL alone, or
a toric IOL combined with a CTR.
Two toric IOL designs were studied: a C-loop haptic IOL and a plate-haptic IOL.
The investigators assessed:
IOL rotation
rotation ≥10 degrees
residual astigmatism
IOL decentration
IOL tilt
corrected distance visual acuity
These were assessed particularly at 1 week and 3 months after surgery.
What did they find?
The most important finding was that the CTR improved early rotational stability.
At 1 week:
Mean rotation was 4.26° without CTR versus 3.20° with CTR.
Rotation of ≥10° occurred in 12.9% without CTR versus 1.8% with CTR.
The multivariate analysis found that CTR use was associated with a substantially lower risk of ≥10° rotation:
RR = 0.21, P = .045.
In other words, within this study, CTR was associated with approximately a 79% lower relative risk of significant rotation.
However, by 3 months, the difference in rotation between the groups was no longer statistically significant.
What happened in very long eyes?
This is perhaps the most clinically interesting part of the study.
In eyes with AL ≥30 mm, CTR implantation was associated with:
less IOL rotation at 1 week,
less residual astigmatism at 1 week, and
delayed occurrence of ≥10° rotation.
The Kaplan-Meier analysis also showed a significant difference in the timing of significant rotation in the AL ≥30 mm subgroup.
This suggests that the benefit of CTR may become more relevant as the eye becomes extremely elongated.
What about IOL design?
The study found that the particular plate-haptic IOL had a higher risk of ≥10° rotation than the particular C-loop IOL:
RR = 6.613, P = .01.
Importantly, this should not be interpreted as proving that all plate-haptic IOLs rotate 6.6 times more than all C-loop IOLs. The study compared two specific IOL models.
Interestingly, in the plate-haptic subgroup, CTR implantation significantly reduced IOL tilt:
2.03° without CTR versus 0.96° with CTR, P = .005.
What happened to centration and tilt?
At 3 months, CTR implantation was associated with significantly less IOL decentration:
0.43 mm without CTR versus 0.28 mm with CTR.
However, there was no significant difference in overall IOL tilt between the CTR and control groups. There was also no significant difference in corrected distance visual acuity between the groups.
What can clinicians take from this study?
The practical lesson is that CTR may be particularly useful when there is concern about capsular-bag stability in highly myopic eyes, especially in extremely long eyes with AL ≥30 mm. The study provides a rationale for considering CTR when implanting a toric IOL in an anatomically challenging, highly elongated eye.
It also reminds us that IOL design matters. The interaction between the haptic architecture and the capsular bag may influence postoperative rotational stability.
What should clinicians NOT conclude?
This study does not prove that every highly myopic eye requires a CTR.
It does not establish that:
CTR permanently prevents toric IOL rotation;
CTR improves visual acuity in all highly myopic eyes;
every plate-haptic IOL is inherently 6.6 times more likely to rotate;
axial length alone determines IOL stability; or
CTR is universally superior to no CTR.
The study was relatively small, single-center, and non-randomized, and it evaluated only two specific toric IOL models.
The Take-Home Message
So, my take-home message from this study would be:
Toric IOL stability is a biomechanical interaction between the capsular bag, zonules, and IOL design. High axial length may adversely influence all three. A CTR can provide additional capsular support and, in this study, improved early rotational stability—particularly in eyes with AL ≥30 mm.
But the decision to use a CTR should remain individualized, based on the anatomy of the eye, the expected capsular stability, and the characteristics of the IOL being implanted.
A second study by Lin et al., published in the Journal of Cataract & Refractive Surgery in 2025, looked specifically at plate-haptic toric IOLs with and without a capsular tension ring.
This was a prospective randomized paired-eye study involving 93 patients, or 186 eyes. Each patient's two eyes were randomized, with one eye receiving a CTR and the fellow eye receiving the same plate-haptic toric IOL without a CTR. Patients were followed for 12 months.
What did they find?
The CTR group showed less toric IOL rotation during the early postoperative period.
The important finding was that the IOL stabilized approximately:
within 1 week with a CTR
compared with approximately 2 weeks without a CTR.
At 2 weeks, residual astigmatism was also lower with the CTR:
0.49 D vs 0.61 D, P = .036.
The benefit was particularly apparent in eyes with characteristics suggesting a larger capsular bag, including:
AL ≥26 mm
WTW ≥11.6 mm
lens thickness ≥4.5 mm
and ACD <3.2 mm.
The authors proposed that the CTR may stabilize the IOL by expanding/supporting the equatorial capsular bag, increasing IOL–capsule contact and friction, and reducing the available space for IOL movement during the early postoperative period.
An important clinical message
The CTR reduced rotation but did not completely eliminate it. Six eyes required repositioning—five without CTR and one with CTR.
So the message from this study is:
CTR appears to be particularly useful for controlling early rotation of plate-haptic toric IOLs, especially when biometric parameters suggest a relatively large capsular bag.
And this study fits very nicely with the previous paper:
Lin et al. → CTR accelerates early stabilization, particularly in eyes with larger anatomical dimensions.
Sun et al. → CTR appears particularly beneficial in very long eyes, especially AL ≥30 mm, and reduces early rotation and decentration.
Together, these studies support the concept that the anatomy of the capsular bag—not simply the choice of toric IOL—is an important determinant of rotational stability.
