Femtosecond laser assisted cataract surgery in a cataract patient with low vaulted ICL following LASIK: a case report

Abstract

Background

Apart from the conventional utilization of ICL implantation for the correction of refractive errors, its recent applications extend to correcting refractive errors post laser refractive surgery. Notably, the development of cataracts stands out as a prevalent postoperative complication, often associated with low vault. Previous cases have demonstrated successful management of cataracts with ICL through the combination of FLACS and ICL removal coupled with IOL implantation, resulting in favorable postoperative visual outcomes. Herein, we present a case of cataract with low vault ICL following LASIK and its subsequent management.

Case presentation

A 46-year-old male presented with vision loss in the right eye for 9 months, and he had undergone LASIK 22 years prior and had ICL implantation in both eyes 2 years ago to correct refractive error. One day after ICL implantation, both eyes exhibited the UDVA of 1.2 and 1.0, well-positioned ICLs, and approximate vault of 150 μm and 200 μm. Six months ago, the patient became aware of blurred vision in the right eye for a duration of 3 months. Examination revealed cloudy lens cortex in the right eye. During the current review, the UDVA of the right eye was 0.6, where nasal wedge-shaped clouding was evident and worsened, while the left eye lens remained transparent. AS-OCT demonstrated the vault of 54 μm in the right eye and 83 μm in the left eye. Considering the patient’s history of LASIK and the presence of right eye cataract, a monovision approach was adopted. The patient underwent FLACS combined with ICL extraction and monofocal IOL lens implantation in the right eye. At 10 days postoperatively, the patient exhibited the UDVA of 1.0.

Conclusions

Our report confirms the feasibility of FLACS in managing cataracts in patients with low vault ICL following LASIK. This procedure does not pose significantly greater challenges than in typical cataract cases, although meticulous care remains essential throughout every step of the surgery, particularly during laser scanning and positioning. With adequate preoperative preparation and precise calculation of the IOL power, surgical outcomes can meet expectations fully.

Background

Implantable collamer lenses (ICL) implantation has been reported to offer superior postoperative visual quality compared to keratoconus surgery, with the advantages such as high predictability, reversibility, and rapid vision recovery [1–3]. Beyond its primary use for refractive error correction, ICL implantation has emerged as a successful approach for refractive correction following keratoconus in recent years [4–8]. Cataract formation, a frequently observed complication after ICL implantation, has been associated with low vault [9, 10]. Femtosecond laser-assisted cataract surgery (FLACS) combined with ICL extraction and posterior chamber implantable ocular lens (IOL) implantation has demonstrated efficacy in managing cataract patients with ICLs, yielding satisfactory visual outcomes [11–15]. We present a case of cataract recurrence following ICL subsequent to laser in situ keratomileusis (LASIK) and its management.

Case presentation

A 46-year-old male presented with vision loss in the right eye for 9 months, and he had undergone LASIK in both eyes 22 years prior and had ICL implantation in both eyes 2 years ago to correct refractive error. Prior to ICL implantation, the uncorrected distance visual acuity (UDVA) was 0.05 and the corrected distance visual acuity (CDVA) was 0.9 (-8.25-1.75*90 D) in the right eye, and the UDVA was 0.2 with the CDVA of 0.9 (-5.75 D) in the left eye. Corneal thickness measured 503 μm and 499 μm in both eyes, horizontal white-to-white (HWTW) diameter was 10.7 mm, anterior chamber depth was 2.99 and 2.93 mm, and anterior chamber volume was 151 and 140 mm2 in both eyes, respectively (Fig. 1). Corneal endothelial cell counts were 2682 and 2701 cells /mm² (SP-3000P, Topcon, Japan). The right eye underwent surgery first, which implantation of the ICL (12.1 mm, -9.50 D). Two hours post the implantation, the vault was shown to be 90 μm by anterior segment optical coherence tomography (AS-OCT; CASIA2, Tomey, Japan) (Fig. 2A), and the posterior surface of the ICL was observed to have no contact with the anterior capsule of the crystalline lens by slit-lamp microscopy. Later in the afternoon, the left eye underwent surgery with an ICL (12.6 mm, -7.00 D) implantation. One day after surgery, both eyes exhibited the UDVA of 1.2 and 1.0, clear corneas, well-positioned ICLs, and approximate vault of 150 μm and 200 μm in both eyes, respectively, as observed by slit lamp microscopy.

Fig. 1.

The anterior segment parameters prior to ICL implantation

Fig. 2.

The vault at two hours post-operation (A) and at the latest follow-up (B) in the right eye by AS-OCT

Six months ago, the patient became aware of blurred vision in the right eye for a duration of 3 months, with the UDVA of 0.6. The patient was diagnosed with a cortical cataract in the right eye and was recommended for follow-up observation. During the current review, the UDVA of the right eye was 0.5, the CDVA was 0.6 (-0.50-1.75*80 D), and the UDVA of the left eye was 1.2. The corneal endothelial cell counts of both eyes were 2,536 and 2,620 cells /mm². A slit-lamp biomicroscopic examination of both eyes with the ICL in place revealed significant clouding in the nasal of the right eye lens, which had aggravated compared to the previous assessment; however, the left eye lens remained transparent. AS-OCT indicated the vault of 54 μm in the right eye (Fig. 2B) and 83 μm in the left eye, both showing a decrease from the postoperative period.

As the patient had previously undergone LASIK and the cataract surgery was exclusively performed on the right eye, a monovision design with a monofocal IOL implantation was recommended. Following the patient’s consent, the right eye underwent FLACS along with ICL removal and IOL lens implantation. A 5.3 mm diametric capsulotomy with 8 µJ energy was executed using the LenSx laser system (LenSx Laser, Alcon, USA). The procedure yielded a smooth scan (Fig. 3A), the resulting capsulotomy displayed a favorable appearance, and there were numerous small bubbles between the ICL and the lens (Fig. 3B). Nucleotomy pretreatment was omitted, and the ultrasonic emulsification was proceeded directly. A traditional 2.8 mm corneal incision was carried out situated at the surgeon’s customary zero o’clock. And then the ICL was removed perpendicular to its longitudinal axis with alternate hands. Subsequent to ICL removal, the capsulorhexis was torn in alignment with the laser trajectory. Following routine ultrasonic emulsification, the IOL (SN60WF, Alcon, USA) of 8.5 D (-1.27 D reserved) according to the Barrett True-K formula by IOL Master 700 (Carl Zeiss, Germany) was implanted into the capsular bag. At 10 days postoperatively, the patient exhibited the UDVA of 1.0 in the right eye.

Fig. 3.

The clouding in the nasal of the right eye lens and the laser assisted capsulotomy yielded a smooth scan (A) and numerous small cavitation bubbles dispersed to the central area (B)

Discussion and conclusions

This study reports a case of a patient who underwent LASIK for refractive correction 22 years ago, followed by ICL implantation for residual refractive error 2 years ago. Despite lacking information on the initial surgery and the patient’s specific pre-LASIK parameters such as refractive diopter and corneal curvature could not be obtained, favorable vision outcomes were achieved post-ICL implantation. Numerous studies have highlighted ICL implantation as a safe and effective approach to mitigate secondary corneal damage in patients experiencing regression following keratorefractive surgeries like RK, PRK, LASIK, etc. In recent years, ICL implantation has emerged as a viable option for addressing residual refractive errors subsequent to IOL implantation in cataract patients who previously underwent keratorefractive surgeries [6–8]. Nine months prior to presentation, the patient noticed a decline in vision in the right eye, and subsequent examination revealed cloudy lens cortex with reduced vault. A recent review corroborated a significant increase in the degree of clouding. In recent years, ICL implantation has emerged as a viable option for addressing residual refractive errors subsequent to IOL implantation in cataract patients who previously underwent keratorefractive surgeries [6–8]. Nine months prior to presentation, the patient noticed a decline in vision in the right eye, and subsequent examination revealed cloudy lens cortex with reduced arch height. A recent review corroborated a significant aggravated of clouding.

Cataract is one of the most prevalent complications following ICL implantation, typically presenting as anterior subcapsular clouding. Its reported incidence in the literature stands at around 3% at 1 year postoperatively, 4–11% at 2 years, 7–13% at 5 years, 20% at 8 years, and 28-58.4% at 10 years [16–20]. Over recent years, advancements in ICL design and surgical expertise have contributed to a decline in cataract incidence. Various studies have identified low vault as a predisposing factor for cataract development. This association may be attributed to the increased likelihood of ICL contact with the mid-peripheral part of the lens in individuals with a low central vault, leading to initial clouding in the periphery that gradually progresses towards the optic axis, culminating in vision impairment [9, 10, 21]. Nevertheless, there is no clear definition of an ideal vault range currently. The STAAR recommends a postoperative vault range of 250–750 μm. However, some scholars believe that as long as the postoperative anterior chamber angle and function are normal, a lower limit of 50 μm for vault is acceptable [22]. Other studies also suggest a vault range of 90–1000 μm [23]. When visual acuity is substantially compromised, ICL removal combined with ultrasonic emulsification and IOL implantation may be employed as a therapeutic measure.

The requirement for ultrasonic emulsification surgery 5 years after ICL implantation has been documented at 2-4.9% [18], rising to 17-18.7% 10 years after surgery [20, 21]. In our case, cataract onset in the right eye 2 years following ICL implantation and was managed surgically. It was considered that in addition to low vault, ultra-high myopia of the right eye with axis length of 29.63 mm and age of 46 years might also exert influence. FLACS offers advantages over conventional ultrasonic emulsification surgery, including more precise capsulotomy, reduced corneal endothelial cell loss, and superior and quicker visual recovery [24]. Additionally, it is deemed safe and effective for cataract patients with ICL [11–15]. Nonetheless, the presence of ICL and its high refractive index may affect FLACS imaging and laser transmission by blocking the diffusion of cavitation bubbles in the anterior chamber, causing them to accumulate below and interfere with laser delivery. This can result in incomplete capsulotomy, misidentify the posterior surface of the ICL as the anterior capsule, and impact nuclear pre-fragmentation, especially in patients with low vault [12–15, 25]. Hence, meticulous identification and manual adjustment of the procedure are warranted if scanning errors occur, while optimizing capsulotomy setup parameters to ensure successful surgery [13]. In our case, because of the remaining vault of 54 μm, the small cavitation bubbles smoothly dispersed to the center of the capsule, preventing the formation of large bubbles. This resulted in the successful completion of both anterior capsule laser scanning and capsulotomy without modifying intraoperative parameters, despite the low vault. Chinese scholars reported that unsuccessful nuclear pre-fragmentation occurred in both low vault and “0” vault eyes [14]. Although pre-fragmentation was sometimes successfully completed, it was weakened during phacoemulsification [15]. Therefore, we did not use pre-fragmentation in our case.

Multiple publications have advocated for the removal of the ICL through the same temporal incision as the one used for ICL implantation surgery [14, 15], which typically obviates the need for ICL rotation and facilitates direct removal along its longitudinal axis. In this case, the surgeon adopted 3 mm corneal incision with his customary position at 0 o’clock. Subsequently, the ICL was extracted by rotating it such that its longitudinal axis orientation towards the incision, with an alternating hand technique.

Multifocal IOLs have become increasingly popular in recent years, especially among cataracts patients with ICL who are more inclined to choose multifocal IOL implantation to achieve spectacle-free vision [26]. However, patients implanted with multifocal IOLs are more likely to complain of halos and glare. Therefore, although it is not an absolute contraindication to implant multifocal IOLs after keratoconus such as RK, LASIK, and PRK, patients need to be adequately informed of potential poor visual quality due to the reduction in contrast sensitivity [27]. In this case, the patient had undergone LASIK and needed to replace only the right lens for the time being, and the left lens remained clear with good vision. To maximize binocular vision balance, after thorough communication and discussion, the patient ultimately chose to implant a monofocal lens. The patient was 46 years old, and to prevent difficulty in near vision, we considered retaining − 1.00 D of myopia. We also suggested choosing a blue light filtering lens to equalize the brightness between both eyes. Following the operation, the patient achieved excellent UDVA without difficulty in near vision and with minimal perceived difference in binocular vision.

To our knowledge, this case report is the first to document a patient who has successfully undergone three types of refractive surgery: corneal refractive surgery, ICL implantation, and IOL replacement surgery. And the report confirms that FLACS is still feasible for cataracts with low vault ICL following LASIK, and is not significantly more challenging than in typical cataract cases. However, caution should be exercised at every step of the procedure, particularly during laser scanning and positioning. With adequate preoperative preparation and precise calculation of the IOL power, surgical outcomes can meet expectations fully. There are still few reports on FLACS performed after ICL implantation, and further prospective studies are needed to assess its safety and feasibility.

Abbreviations

FLACS

Femtosecond laser-assisted cataract surgery

IOL

Implantable ocular lens

LASIK

Laser in situ keratomileusis

UDVA

Uncorrected distance visual acuity

CDVA

Corrected distance visual acuity

HWTW

Horizontal white-to-white

AS-OCT

Anterior segment optical coherence tomography

Author contributions

YYX drafted the article and revised the manuscript. ZB and CXR did the surgery and drafted the article. WJ collected date and drafted the article. All authors reviewed the manuscript. All authors read and approved the final manuscript.

Funding

Not applicable.

Data availability

All data generated and analyzed during this study are included in this published article.

Declarations

Ethics approval and consent to participate

This case report was approved by the ethics committee of Aier Eye Hospital, Tianjin University.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and any accompanying images.

Competing interests

The authors declare no competing interests.