Evaluation of acquired punctal stenosis using anterior segment optical coherence tomography

Abstract

Background/objectives:

The aim of this article was to study the lower punctum parameters in patients with acquired punctal stenosis using spectral-domain anterior segment optical coherence tomography.

Subjects/methods:

This was a prospective nonrandomized study that included two groups. Group 1 was composed of 32 puncta from 32 subjects (11 males and 21 females, aged 40–62 years) with epiphora and clinically diagnosed punctal stenosis. Group 2 (control group) included 30 puncta from 30 normal subjects (10 males and 20 females, aged 43–63 years). Anterior segment optical coherence tomography was employed to evaluate lower punctum parameters in all subjects; the inner and outer punctal diameters as well as punctal depth were measured.

Results:

External punctal diameter (mean: 466.1 ± 120.3 μm), internal punctal diameter (mean: 173.4 ± 55.6 μm) and punctal depth (mean: 188.4 ± 67 μm) values in Group 1 were statistically significantly lower than those in Group 2 (mean: 745.7 ± 156.9 μm, mean: 384 ± 119.1 μm, and mean: 284.9 ± 57.7 μm, respectively).

Conclusion:

Anterior segment optical coherence tomography could possibly be used as a noncontact and noninvasive diagnostic modality for evaluating and measuring the lower punctum in patients with punctal stenosis. Further research is required to develop a normative database and grading system for stenosed puncta and to correlate the degree of stenosis with the severity of epiphora.

Keywords

Punctal stenosis anterior segment optical coherence tomography optical coherence tomography

Introduction

The punctum is defined as the opening situated on top of the lacrimal papilla present at the medial aspect of the upper and lower lid margins.¹ Understanding the anatomy of the punctum is important in the management of epiphora and dry eye.^2,3 Punctal size is measured by slit lamp,⁴ and punctal stenosis is diagnosed with the finding of a punctal diameter of less than 0.3 mm using probes,⁵ which may be inaccurate.

Anterior segment optical coherence tomography (AS-OCT) was recently used to provide high-resolution images of the punctum.⁶ This is a noninvasive, noncontact imaging technique that employs infrared light to study ocular structures in vivo.⁷

The current study presents the outcomes of OCT imaging and measurements in patients with epiphora and clinically diagnosed punctal stenosis as a step towards clearing this modality for use as a noninvasive diagnostic tool for lower punctal stenosis.

Patients and methods

This study was a prospective, consecutive nonrandomized clinical series of cases approved by the ethics committee of the Faculty of Medicine, Minia University, Minia, Egypt. Written informed consent forms were collected from each subject at the time of their first study visit. This study adhered to the principles outlined in the Declaration of Helsinki. This study was performed from 1st of May 2018 to 1st of November 2018.

The study included 32 puncta from 11 males and 21 females aged between 40 and 62 years (mean: 52 ± 6.2 years) with epiphora and clinically diagnosed punctal stenosis, defined as Group 1. Separately, 30 puncta from 30 normal subjects (10 males and 20 females) aged 43–63 years (mean: 52.8 ± 6.1 years) were established as the control group (Group 2).

Patients in Group 1 were diagnosed clinically with punctal stenosis according to the presence of epiphora, a high tear meniscus of more than 0.2 mm, and the inability to pass the smallest lacrimal probe size 0000 (0.45 mm). Patient selection and clinical evaluations were performed by a single oculoplastic surgeon (R.M.A).

Eyes that met any of the following criteria were excluded from the study: congenital punctal stenosis; punctal agenesis; lid malposition; canalicular, nasolacrimal, sac, or duct obstruction; previous eyelid or lacrimal drainage surgery; untreated conjunctivitis; and blepharitis.

Punctal diameter was clinically evaluated using the largest lacrimal probe that could be inserted through the punctal opening without dilatation under topical anaesthesia. AS-OCT was used to evaluate the lower punctum parameters in all subjects; here, the inner and outer punctal diameters as well as punctal depth were measured.

Technique of OCT examination

Examination of the lower punctum was performed by a single investigator (H.R.A) using a spectral-domain OCT machine (RTVue Model-RT100 CAM System, Version 6.2; Optovue, Inc., Fremont, CA, USA) by attaching the cornea/anterior module (CAM) lens. The CAM lens is a wide-angle, high-magnification lens with a 10-mm working distance. With this approach, the axial resolution was 5 μm, the lateral resolution was 8 μm and the scan beam had a wavelength of 840 ± 10 nm. The two red external light-emitting diodes (LEDs) located on the headrest were approximated on each side of the lower punctum for proper illumination and imaging of the punctum.

Gentle eversion of the medial part of the lower lid was performed to expose the lower lid punctum so that the vertical canaliculus was brought to be located at an axial plane without undue stretching or pressure applied to the lower lid. A line scan was the used examination scan, containing 1020 A-scans/line, with an 8-mm length. The line scan was centred on the lower punctum and parallel to the mucocutaneous junction, as seen in Figure 1.

Measurements of the external punctal diameter, internal punctal diameter and punctal depth were performed by three blinded observers (R.M.A, H.R.A and A.A.A) on the B-scan image of the lower punctum (by selecting it from the ‘review’ window), using a distance measurement tool (Figure 2).

External punctal diameter was measured as a line connecting the highest points on the medial and lateral punctal walls. Internal punctal diameter was measured as a horizontal line located just above the narrowing. The distance between the line representing the external punctal diameter and the floor of the punctum was calculated and designated as the punctal depth (Figure 3).

One eye was selected from each participant according to different criteria, as follows: in Group 1, the eye with more epiphora was chosen (Figure 4), while in Group 2 (control group), the eye with lower dimensions (i.e. lower punctal external, internal and depth values) was selected. Each lower punctum was scanned three times. The mean value for each of the three punctal dimensions was taken, recorded and analysed.

Results

Statistical analysis was performed using the Statistical Package for the Social Sciences for Windows Version 20.0 software programme (IBM Corp., Armonk, NY, USA). Data were normally distributed and tested using the Shapiro–Wilk normality test.

Statistical analysis between the two groups was performed using an independent-samples t-test. A p-value was considered significant if it was less than 0.05. The external and internal punctal diameters were significantly narrower in Group 1 than in Group 2. In addition, punctal depth was significantly smaller in Group 1 (Table 1).

Table 1.

Study results.

	Group 1Cases (N = 32)	Group 2Control (N = 30)	p-value
External punctal diameter (μm)
Mean ± SD	466.1 ± 120.3	745.7 ± 156.9	0.0001*
Range	175–686	352–1120
Internal punctal diameter (μm)
Mean ± SD	173.4 ± 55.6	384 ± 119.1	0.0001*
Range	98–324	271–689
Punctal depth (μm)
Mean ± SD	188.4 ± 67	284.9 ± 57.7	0.0001*
Range	47–347	200–497

p < .05.

Discussion

Epiphora is a frequent complaint, and one of its common causes is punctal stenosis.⁸ Our study used AS-OCT to assess punctal parameters in clinically diagnosed patients with punctal stenosis and compared them with those in normal subjects. The punctum was visualized within an elevated mount corresponding to lacrimal papilla. Clinical utilization of punctal size documentation is essential in patients with punctal stenosis.⁹

There exists a lack of consensus on the definition of punctal stenosis. It can be defined as a diameter of less than 0.3 mm or an inability to intubate the punctum with a 26-gauge cannula.⁹ In the literature, one study described the use of slit lamp photography to map punctal borders using a computer cursor assembly probe and a HiPad digitaliser. However, this measurement technique may have high subjective variability.¹⁰ Elsewhere, Kashkouli et al.¹¹ suggested a grading system for punctal stenosis based on slit lamp examination of the external lacrimal punctum (ELP). However, acquired external punctal stenosis (AEPS) may or may not be associated with internal punctal and canalicular stenosis.¹² Therefore, a proper evaluation of the proximal lacrimal system (punctum and vertical canaliculus) should be completed using an objective method in cases of acquired punctal stenosis.

AS-OCT is an established noncontact imaging modality that uses infrared light with a wavelength of 840 nm to provide informative structural images of the anterior segment. These images could be used for qualitative and quantitative assessments of the anterior segment and proximal lacrimal system structures.

Wawrzynski et al.,⁶ who conducted their study on 36 puncta of 18 healthy subjects with no symptoms of epiphora (asymptomatic), were the first to demonstrate in vivo high-resolution spectral-domain OCT images of the normal proximal lacrimal system using the Topcon 3D 2000 system (Topcon Corp., Tokyo, Japan).

Previous OCT studies of the lower lacrimal punctum reported a wide value range for punctal diameter in healthy subjects. Our results were in agreement with those of Timlin et al.,¹³ especially for external punctal diameter, as we used the same measurement locations described in their study. The external punctum diameter was measured from a tangent connecting the highest points on the nasal and temporal punctal walls, which is a well-defined location that cannot significantly vary from observer to observer, unlike in the case of the measurements taken within the tapering punctum in previous OCT studies,^6,14,15 as seen in (Table 2).

Table 2.

Summary of reported findings from AS-OCT examination of the lower lacrimal punctal region.

Study	Current study		Singh et al.¹⁶	Timlin et al.¹³	Allam and Ahmed¹⁴	Kamal et al.¹⁵	Wawrzynski et al.⁶
Study	Group 1	Group 2	Singh et al.¹⁶	Timlin et al.¹³	Allam and Ahmed¹⁴	Kamal et al.¹⁵	Wawrzynski et al.⁶
No. of patients (eyes)	32 (32)	30 (30)	100 (200)	20 (40)	76 (147)	52 (103)	18 (36)
Age (years)Mean ± SD	52 ± 6.2	52.8 ± 6.1	24.14 ± 4.8	39 ± 10.1	44 ± 14.35	25.6 ± 5.5	Not described in publication text
Study population	Patients with acquired punctal stenosis	Healthy control	Healthy subjects	Healthy subjects	Healthy subjects	Healthy subjects	Healthy subjects
Machine used	SD AS-OCT RTVue Model-RT100 (Optovue, Inc.)		AS-OCT (Visante OCT Model 1000 System Software Version 3.0	Heidelberg Spectralis	SD AS-OCT RTVue Model-RT100 (Optovue, Inc.)	FD-OCT RTVue scanner with 3D (Optovue, Inc.)	Topcon 3D OCT 2000
Direction of scan	Line scan was centred on the lower punctum and parallel to mucocutaneous junction		Axial images with high resolution were selected	Parallel to mucocutaneous junction	Image shows two lines: one parallel and one perpendicular to mucocutaneous junction	Image shows horizontal line, not aligned to eyelid margin	Image shows horizontal line, not aligned to eyelid margin
EP size	466.1 ± 120.3 µm	745.7 ± 156.9 µm	382.2 ± 103.14 µm	646 ± 150 µm	412 ± 163 µm	215 ± 73 µm	247 ± 78 µm
Location of EP measurement	A line connecting highest points on the medial and lateral punctal walls		At the surface of the punctum	Tangent connecting the highest points on the nasal and temporal punctal walls	Image shows within punctum with no prescribed depth	Image shows within punctum with no prescribed depth	Image shows within punctum with no prescribed depth
IP size	173.4 ± 55.6 µm	384 ± 119.1 µm	140.7 ± 67.29 µm	50 ± 104 µm	234 ± 139 µm	125 ± 61 µm	110 ± 67 µm
Location of IP measurement	A horizontal line just above the narrowing		Measured at hyper-reflective band of tissue around 40–50 µm from surface	Measured at 500 µm from EP tangent	Measured just above the narrowing	Measured midway between punctum opening and visible lower end	Not described in publication text
VCD	188.4 ± 67 µm	284.9 ± 57.7 µm	811.8 ± 253.7 µm	544 ± 327 µm	252 ± 127 µm	890 ± 155 µm	753 ± 216 µm
Location of VCD measurement	Distance between the line representing the external punctal diameter and the floor of the punctum		From EP to thickened elevated mucosa at the junction between punctum and vertical canaliculus	Vertically from tangent	Perpendicular to tangent	Not described in publication text	Not described in publication text

AS-OCT: anterior segment optical coherence tomography; SD: standard deviation; EP: external punctum; IP: internal punctum; FD: Fourier domain; VCD: vertical canaliculus depth.

In our study, we assessed punctal parameters in clinically diagnosed patients with punctal stenosis and epiphora (Group 1) and compared these parameters with those of normal subjects (Group 2).

External punctal diameter, internal punctal diameter and punctal depth values in the punctal stenosis group were 466.1 ± 120.3 µm, 173.4 ± 55.6 µm and 188.4 ± 67 µm, respectively, which were significantly lower values than those in normal subjects, which were 745.7 ± 156.9 µm, 384 ± 119.1 µm and 284.9 ± 57.7 µm, respectively. A wide range of external punctal diameter in cases of punctal stenosis may be due to variability in the shape of the external punctum, where each shape has its own character. Hur et al.¹⁷ classified punctal stenosis shapes into the following types: membranous, slit, horseshoe and pinpoint, depending on the shape of the external punctum opening. These different shapes exhibit definite differences in size, with a particularly wide range present regarding external punctal diameter size.¹⁷ Also, the wide age range in the current study may be a contributing factor to the external punctal size variability. The inclusion of patients of older ages should be considered, as older age has been reported by some previous studies to be an etiological factor for punctal stenosis.^11,18 The assumed pathogenesis is involutional changes and tissue atrophy affecting the external punctum, altering the punctum into a dense fibrous structure and resulting in its narrowing or occlusion.^11,18,19 In addition to the shape of the puncta and age of the patients, another factor that was explained by Kashkouli et al.¹¹ as leading to variability was gender, as postmenopausal hormonal changes were suggested to have an influence.

In the current study, female patients represented 65% of cases among the stenotic group. This was in agreement with the findings of Kashkouli et al.¹¹ and Offutt et al.,²⁰ as both groups of researchers experienced female predominance rates in their studies of 70% and 71%, respectively.

Time-domain AS-OCT machines have longer wavelengths, with deeper tissue penetration resulting in images highlighting more details of the proximal lacrimal system, as reported by Singh et al.,¹⁶ who recorded a longer vertical canalicular depth (811.8 ± 253.7 µm) when compared with either group in our study population (188.4 ± 67 µm in patients with acquired punctal stenosis and 284.9 ± 57.7 µm in the control group).

Study limitations

Further studies may be needed to correlate the findings of this examination modality with other clinical findings, surgical procedures and surgical outcomes through the development of a grading system for the severity of punctal narrowing, guidelines for the surgical procedures, questionnaires regarding the improvement of patients’ symptoms of epiphora and postoperative anterior segment evaluations. Our ongoing research is on AS-OCT evaluation before and after implantation of perforated lacrimal plugs in cases of punctal stenosis. Another limitation is the difficulty of examining deeper tissues as distal and/or common canaliculus, due to the inherent properties of the examining light beam, which cannot penetrate deeply into the tissues. A larger sample size is required, which may be helpful to develop a scoring system in cases of punctal stenosis.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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