Higher Order Aberrations in Patients with Unilateral Nasolacrimal Duct Obstruction
Article information
Abstract
Purpose
To compare corneal higher order aberrations (HOAs) in patients with epiphora caused by unilateral primary acquired nasolacrimal duct obstruction (PANDO) and their fellow eyes.
Methods
A total of 122 eyes of 61 patients with unilateral PANDO were included. Affected eyes were named as group 1 and contralateral eyes as group 2. The Munk score and fluorescein dye disappearance test (FDDT) were assessed. Corneal topographic and HOAs measurements were taken by Sirius topography.
Results
There were 47 female and 14 male patients. The mean keratometry was 43.84 ± 1.4 in group 1 and 43.96 ± 1.4 in group 2 (p = 0.73). The mean corneal topographic astigmatism was 0.81 ± 0.7 in group 1 and 0.78 ± 0.5 in group 2 (p = 0.57). The mean coma-like aberration was 0.19 ± 0.2 in group 1 and 0.10 ± 0.1 in group 2 (p = 0.03). The mean spherical-like aberration was 0.16 ± 0.1 in group 1 and 0.11 ± 0.1 in group 2 (p = 0.04). The mean total corneal HOA was 0.30 ± 0.5 in group 1 and 0.23 ± 0.2 in group 2 (p = 0.04). The mean Munk score was 3.47 ± 1.0 in group 1. There was a positive correlation between the Munk score and both coma-like aberration (r = 0.53, p = 0.003) and total corneal HOAs (r = 0.44, p = 0.010). The mean FDDT grade was 2.60 ± 0.1 in group 1. A positive correlation was observed between the FDDT grade and both coma-like aberration (r = 0.48, p = 0.001) and total corneal HOAs (r = 0.33, p = 0.001).
Conclusions
Epiphora in patients with PANDO can affect corneal HOAs. As patients’ symptoms and tear pooling were increased as corneal HOA levels increased.
Epiphora is the main complaint of primary acquired nasolacrimal duct obstruction (PANDO). Physical and social negative effects of epiphora have been demonstrated by quality of life (QoL) and vision-related QoL questionnaires [1–4]. Blurry vision, visual quality change throughout the day, difficulty in reading and driving, and frequent blinking are the vision-related complaints.
Since the tear film is the first refractive component of the eye, both dry eye and epiphora have a strong effect on quality of vision [5–8]. Although detection of vision is mainly based on visual acuity (VA) tests, more specific tests are needed to document quality of vision. Corneal topography and wavefront measurements, contrast sensitivity testing, and functional VA tests are the methods to detect visual deteriorations.
In our study, we aimed to show the difference of corneal wavefront aberrations in patients with unilateral PANDO with their normal eyes. Additionally, we aimed to assess the relationship between corneal higher order aberrations (HOAs) and the severity of epiphora.
Materials and Methods
Ethics statement
The study was approved by the Institutional Review Board of Medeniyet University Goztepe City Hospital (No. 0568). Written informed consent was obtained from all participants. All procedures were performed following the ethical standards of the Declaration of Helsinki for human subjects.
Study design and setting
This prospective study was conducted in the Medeniyet University Goztepe City Hospital (Istanbul, Turkiye) from September 2022 to March 2023. Patients who referred to our oculoplastic clinic with unilateral PANDO were enrolled in the study. Baseline ophthalmologic examinations including anterior and posterior segment and intraocular pressure measurement were done to all of the participants. Corneal keratometric and wavefront measurements were taken by Sirius topography (CSO) from both eyes. The data were analyzed from the central 6 mm in diameter up to the sixth order of Zernike polynomials. Coma-like aberrations, spherical-like aberrations, and total corneal HOAs were noted. Measurements were done by the same physician (FS) after first blinking of the patients.
Nasolacrimal irrigation test was used to diagnose PANDO. Test was done under topical anesthesia with saline irrigation from the canaliculi. Patients with a negative irrigation test unilaterally were enrolled in the study. Affected eyes with PANDO were named as group 1 and contralateral normal eyes as group 2.
The severity of epiphora was assessed by the Munk score. Patients were asked to grade epiphora severity subjectively based on the Munk scale [9]. The scale was graded as follows: 0, no epiphora; 1, occasional epiphora requiring drying or dabbing less than twice daily; 2, epiphora requiring dabbing two to four times daily; 3, epiphora requiring dabbing five to 10 times daily; and 4, epiphora requiring dabbing more than 10 times daily or constant epiphora.
Fluorescein dye disappearance test (FDDT) was done in eyes with PANDO. One drop of 2% fluorescein dye was dropped to affected eye. After 5 minutes remaining fluorescein was graded under cobalt blue filter of slit-lamp. The test was based on the modification of FDDT grading by MacEwen and Young [10]. The FDDT grading was defined by Zappia and Milder [11]: grade 0, no fluorescence in the conjunctival sac; grade 1, thin fluorescein marginal tear strips only; grade 2, between grades 1 and 3; and grade 3, wide and bright fluorescein strip.
Statistical analysis
Statistical analysis of the data was performed by using IBM SPSS ver. 22.0 (IBM Corp). Descriptive statistics were given as mean ± standard deviation. The Shapiro-Wilk test was used to test the normal distribution of the variables. In the comparison of the values the paired t-test was used for the normally distributed data, whereas the Mann-Whitney U-test was used for the non-normally distributed data. Pearson and Spearman correlation analysis was used to investigate the relationship between two variables. A p-value less than 0.05 was considered as statistically significant.
Results
The study was composed of 122 eyes of 61 patients. There were 47 female patients (77%) and 14 male patients (23%) in the study group. The mean age was 56.67 ± 5.1 years (range, 32–72 years). Thirty-eight patients had nasolacrimal duct obstruction in the right eye and 23 patients in the left eye. The mean best-corrected VA was 0.94 ± 0.1 in group 1 and 0.95 ± 0.1 in group 2 (p = 0.74). The mean standard error was 0.90 ± 0.9 in group 1 and 0.77 ± 0.7 in group 2 (p = 0.87). The mean keratometry was 43.84 ± 1.4 in group 1 and 43.96 ± 1.4 in group 2 (p = 0.73). The mean corneal topographic astigmatism was 0.81 ± 0.7 in group 1 and 0.78 ± 0.5 in group 2 (p = 0.57). Paired t-test was used in each of the comparisons.
The mean coma-like aberration was 0.19 ± 0.2 in group 1 and 0.10 ± 0.1 in group 2 ( p = 0.03). The mean spherical-like aberration was 0.16 ± 0.1 in group 1 and 0.11 ± 0.1 in group 2 (p = 0.04). The mean total corneal HOAs was 0.30 ± 0.5 in group 1 and 0.23 ± 0.2 in group 2 (p = 0.04) (Table 1). Mann-Whitney U-test was used in each of the comparisons.
The mean Munk score was 3.47 ± 1.0 (range, 1–5) in group 1. According to the Spearman correlation analysis there was a statistically significant positive correlation between the Munk score and both coma-like aberration (r = 0.53, p = 0.003) and total corneal HOAs (r = 0.44, p = 0.010). There was a positive statistically nonsignificant correlation between the Munk score and spherical-like aberration (r = 0.17, p = 0.340).
The mean FDDT grade was 2.60 ± 0.1 (range, 2–3) in group 1. According to the Pearson correlation analysis there was a positive correlation between the FDDT grade and both coma-like aberration (r = 0.48, p = 0.001) and total corneal HOAs (r = 0.33, p = 0.001). There was a positive but statistically nonsignificant correlation between the FDDT grade and spherical-like aberration (r = 0.44, p = 0.090) (Table 2).
Discussion
Epiphora caused by PANDO is one of the most common ocular complaints in ophthalmology practice. Patients suffer from visual alterations due to epiphora such as difficulty in driving or reading. Besides of lower order aberrations, HOAs cannot be corrected with the spectacles which have an impact on the image quality [12]. In cases of epiphora, HOAs are likely to be the cause of visual alterations. Therefore, we aimed to analyze the differences of HOAs between the eyes of the each patient. According to our results, even though the VA levels were similar between the eyes of each patient, coma- and spherical-like aberrations, and total corneal HOAs were significantly different. Moreover, keratometry values, corneal astigmatism, and standard error levels were similar between the eyes that may affect the corneal HOAs.
Coma- and spherical-like aberrations are clinically important aberration types from Zernike polynomials. Coma is characterized by double vision which causes the light to be scattered like the tail of the comet in the night. Spherical aberration is characterized by halos, ghost images, altered contrast sensitivity, and starburst in mesopic conditions. These aberrations are directly related with anterior corneal surface and tear film integrity [13].
Blinking times have an effect on sequential corneal HOA measurements [14]. Because of this reason we measured the corneal HOAs once after first blink of the patients. Koh et al. [15] reported that 1 month after the lacrimal passage intubation surgery, functional VA was improved, blink frequency was decreased, corneal aberrations (coma- and spherical-like aberrations and HOAs) were decreased, and tear meniscus dimension was decreased in patients with epiphora. They indicated that lacrimal passage patency provides improvement in visual function and optical quality. The different point of our study was we compared the affected and nonaffected eyes of each patient. Even before the lacrimal surgery, HAOs of the affected eyes were statistically different than fellow eyes in our study.
Tasaki et al. [16] studied the effect of epiphora on contrast sensitivity. They have shown that the area under the log contrast sensitivity function was significantly lower in the eyes with epiphora than that in the normal fellow eyes. They underlined that visual disturbances could be the indication for the lacrimal intubation surgery besides dacryocystitis and conjunctivitis.
In contrast to epiphora, there are many studies about effect of dry eye on corneal aberration and optical quality in the literature [7,17–19]. Studies have shown that tear film distortion caused by dry eye result increment in HOAs compared with normal eyes. In addition, the use of lubricating eye drops for dry eye improves visual performance and reduces corneal aberrations [20–22]. Based on the literature, tear film instability caused by epiphora or dry eye has influence on visual quality and both could be reversible after treatment.
The FDDT is as important as the irrigation test to evaluate nasolacrimal passage [23]. We have shown that FDDT grades have positive correlation with coma-like aberration and total corneal HOAs. Both Koh et al. [15] and Taniguchi et al. [24] reported decrease in tear meniscus dimension and HOAs after nasolacrimal surgery. To the best of our knowledge, our study was the first study showing correlation between FDDT grades and corneal HOAs. In summary as the tear volume on the eyelid increased the quality of vision was affected.
According to the literature, Munk scores of the patients were decreased after nasolacrimal surgeries [25–27]. We assumed that optical quality may correlate with the Munk scores. In our study we demonstrated that coma-like aberration and total corneal HOAs correlate with the Munk scores as well as the FDDT grades. This means that dabbing times of patients may also reflect their visual disturbance.
The limitation of our study was deficiency of tear meniscus height and tear meniscus area measurements by anterior segment optical coherence tomography, as they can be accepted as more objective than the FDDT grades. Another limitation was the sample size of the study. Studies with a larger number of patients are needed.
In conclusion, visual quality in epiphora cases has not yet been entirely researched. We have demonstrated that epiphora causes increase in coma- and spherical-like aberrations and total corneal HOAs and they were positively correlated with FDDT grades and Munk scores in affected eyes. Further studies are needed to understand the effect of epiphora on visual disturbances objectively.
Acknowledgements
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Notes
Conflicts of Interest
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Funding
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