Facilitators and Barriers to Using Selective Laser Trabeculoplasty (SLT) as First-Line Treatment for Glaucoma: Physician and Patient Views Gathered during an Exploratory Descriptive Qualitative Study

ABSTRACT Purpose To explore the perception of selective laser trabeculoplasty (SLT) among physicians and patients and the acceptance of using SLT as first-line treatment for glaucoma. Methods Exploratory descriptive qualitative study based on semi-structured interviews with glaucoma specialists and patients in two eye hospital of Zhejiang and Guangdong Provinces, China. Data were analyzed using the thematic analysis framework approach. Results 11 glaucoma specialists and 12 glaucoma patients were interviewed. Four themes were identified in the data: Physicians’ preferences for treatment types, patient views on treatment types, decision-making during the physician-patient encounter and feasibility of SLT as a first-line therapy. Advantages of SLT include safety and repeatability with limited side effects. However, concerns about the durability of the effect of the treatment were often mentioned by both physicians and patients. Some factors such as practice preference, personal motivation and patient characteristics may influence treatment choice. Most patients lack knowledge about SLT and hold high expectations of their treatments. Physicians report insufficient evidence supporting the use of SLT as first line therapy. Physicians report the need for locally relevant, evidence-based guidelines regarding the use of SLT in the treatment of glaucoma. Conclusions SLT was suggested as the first-line treatment of glaucoma due to its reliable efficacy and potential advantage. Results from our study offer important insight into barriers of increasing the uptake of SLT, which also provides some guidance for the use of SLT in the future.


Introduction
Glaucoma is one of the three leading causes of blindness in China. From 2020 to 2050, the prevalence of glaucoma in China is expected to increase from 2.64% to 3.48%. Likewise, the prevalence of primary open angle glaucoma (POAG) will also increase from 1.05% to 1.33%, a 27% increase. 1 Lowering intraocular pressure (IOP) is the only way to avoid increasing visual field defects in glaucoma patients. 2 At present, topical medications, laser treatment and surgery are all used to lower IOP, but are unable to reverse existing vision loss.
Selective laser trabeculoplasty (SLT), introduced by Latina et al 3 in 1995, delivers laser energy to the pigmented trabecular meshwork, which is proven to reduce IOP in primary open angle and a variety of secondary glaucoma. Benefits include a short recovery time, few side effects, good safety record and the potential for repeatability if the desired pressure reduction is not achieved. [4][5][6][7] Despite the proven safety and efficacy of SLT as a first line therapy as established in a number of randomized controlled trials, 5,6 the uptake of SLT in China appears to be far less frequent than that in Europe or the United States. [8][9][10][11][12] The present study explored facilitators and barriers to using SLT as first-line glaucoma treatment based on the views of glaucoma specialists and patients at two eye hospitals in China.

Study design
This exploratory descriptive qualitative study is based on interview data from glaucoma patients and specialists. Information about the perception of the relative advantages and disadvantages of SLT versus other IOP-reducing treatments, factors affecting glaucoma treatment decision-making and barriers to using SLT as first-line treatment for glaucoma in China. The study protocol was approved by the Ethics Committee of the Wenzhou Medical University. Oral or written informed consent was obtained from all participants prior to interviews. All procedures were carried out in accordance with the Declaration of Helsinki. Interviews were conducted from July to October 2020.

Sample size and study setting
In qualitative research, sample size is based on the number of participants needed to reach thematic saturation (the point where no new information emerges and all identified themes are well understood and supported by the data). 13 Based on prior experience, the sample size planned to reach saturation was between 22 and 30 participants. Participants were recruited from two tertiary-level municipal hospitals, in Wenzhou, Zhejiang Province, and Guangzhou, Guangdong Province. Criterion-based purposive sampling was used, meaning patients were drawn from each treatment option group (laser, incisional surgery, topical medications) and physicians had varying degrees of experience. The aim was to include patients and physicians from both provincial hospitals. However, patients were not recruited from Guangzhou because there were no staff to recruit patients in the participating hospital.

Physicians
A post-graduate ophthalmology student contacted registered glaucoma specialists working in the two participating hospitals. The student followed a recruitment script to explain the study and invite potential participants to join the project. Twelve specialists were contacted and 11 (91.7%) joined the study. All interviews were done by researchers in Wenzhou, so physicians in Guangzhou were interviewed by phone and those in Wenzhou were interviewed in person.

Patients
A glaucoma clinic nurse at Wenzhou Medical University reviewed patient records to identify eligible persons to invite into the study. The nurse made up to three phone calls to contact each eligible patient, following a recruitment script when a potential participant was reached. The name, contact information and sampling characteristics of interested patients were provided to an interviewer who answered participant questions and scheduled interviews. Fifteen patients were identified and 12 (80.0%) were enrolled in the study. Recruitment continued until at least two male and two female patients undergoing each type of treatment were recruited, and preliminary analyses indicated that saturation had been reached. No patients were recruited in Guangzhou because researchers were in Wenzhou and there were no staff to recruit patients in Guangzhou.

Data collection instruments
Two semi-structured, parallel interview guides were formulated by YC and CP in English and validated by two glaucoma specialists (YL, NC) to ensure the clinical quality and fidelity to the protocol. Following World Health Organization guidelines for translating and adapting research instruments, 14 the guides were translated into Chinese and pilot tested with a physician and a patient to identify difficulties with question sequence or wording. Minor changes were made based on feedback from these pilot interviews and then the latest version was reviewed and finalized by an experienced qualitative expert. Copies of interview guides are provided in the supplementary file.

Interview procedure
Twenty-four hours before a scheduled interview, a research team member contacted the participant to remind them of the upcoming interview. To increase participant convenience, all interviews were conducted in person at the hospital after their scheduled appointment at the eye clinic. Interviews were conducted by two MD ophthalmology trainees (YC, DS) who used probes suggested on the guide to elicit detailed information for each topic. Interviews were conducted in Chinese (Mandarin) and audio taped (ICD-PX440 4GB IC recorders; SONY; Minato, Tokyo, Japan) with participants' permission for subsequent data analysis.

Data analysis
A professional typist created a verbatim transcript from each audio file, removing all identifying information before returning the file to the interviewer. The interviewer compared audio and written versions of each interview to correct errors. Two MD ophthalmology trainees (YC, DS) independently reviewed and coded each transcript following the six steps of the thematic framework analysis approach (familiarization, generating initial codes, searching for themes, reviewing themes, defining and naming themes, producing the report). 15 They reviewed each other's results and discussed themes until reaching consensus. Findings are supported by illustrative quotes presented in italics, with a unique identification number used to indicate the source of each statement (e.g., 'MD11' = 11th physician interviewed). Any modifications of quotes made to improve clarity are indicated by ellipses for deletions and square brackets for added text.
To ensure the rigor of the study, the following steps were taken: recruitment and interviews were performed in accordance with written protocols; participant validation was performed by reviewing information provided during interviews to ensure accuracy; study findings were linked to the raw data using quotes from several participants; and researcher and data source triangulation, or having multiple researchers and sources of data. Team members include two MD ophthalmology trainees (YC, DS), an experienced public health qualitative researcher (LL), and two experienced glaucoma specialists (YL, NC). The consolidated criteria for reporting qualitative research (COREQ) was used to assess the study's rigor. 16

Results
A total of 12 physicians and 15 patients were recruited. However, one physician was unable to attend the interview due to competing clinical duties, reducing the sample size to 11 physicians. Two patients indicated that they had changed their mind and did not wish to be interviewed, and one patient was not interviewed due to recovery from eye surgery, resulting in a final sample size of 12 patients. Participant characteristics are shown in Table 1.
The four themes identified in the data were: physicians' preferences for treatment types; patient views on glaucoma treatments; decision-making during the physician-patient encounter; and facilitators and barriers to using SLT as first-line treatment for open angle glaucoma.

Theme 1 physicians' preferences for treatment type
Physicians based their preference on which treatments to recommend according to glaucoma guidelines and clinical experience. The majority of cases, irrespective of type and stage of glaucoma, were treated with topical medication initially: Physicians also identified several uses for SLT after the initial treatment, ranging from an alternative to topical medicine or surgery, or as adjuvant therapy, with most physicians opting for the latter: In fact, we use SLT less [than other treatments]. For refractory glaucoma or glaucoma with poor IOP control after applying medication or surgery, we might try SLT. (MD4) Physicians generally said SLT could not replace surgery because surgery is much more effective in reducing IOP: As for advanced glaucoma with a great need to decrease IOP, SLT may not work well. So, in that situation, surgery would be our choice. (MD1) The general consensus was that SLT is equivalent in efficacy to using one or two medications, and could therefore be used to reduce the use of topical medications:

Theme 2 patient views on treatment types
Patients reported favorable views on the risk profile and cost of SLT, however, they reported limited understanding of SLT and concerns about the efficacy of a laser treatment. Because SLT is a non-invasive treatment option with limited adverse effects, it is often seen as an acceptable option to patients: Patients hope that the treatment they choose will achieve long-term IOP control without additional visits to the hospital. However, having high expectations about a certain treatment can also lead them to favor of surgery over SLT due to a perceived better cure rate: Patients express that they fear the risks and uncertainty of a given treatment for a disease that has no definitive cure. Many factors including disease severity and the overall physical condition of patients (e.g., whether they can tolerate surgery) all contribute to the physicians' treatment recommendations for their patients: Selecting which kind of treatment is mainly based on patient's condition. I will consider the glaucoma type, stage and condition before choosing treatment strategy.
There is a gap between what physicians describe as actual benefits and what patients expect during decision making: Doctor recommended SLT to me before but I refused and turn to accept surgery directly. Because I thought SLT is not effective enough to lower IOP. (PT10) However, patients' trust in physicians can bridge the gap to an extent, leading patients to accept the specialist's recommendation for treatment: If the patient has a lot of trust in the doctor, it will be easier for the patient to accept this treatment [recommended by doctors]. (PT8).

Theme 4 feasibility of SLT as a first-line therapy
While SLT is considered by many physicians as a first line therapy due to its several advantages, the uptake of SLT in practice is still limited by deficient understanding, local guidelines, and availability of the equipment. Physicians themselves have varying attitudes about whether SLT can be promoted as first-line treatment for glaucoma. Factors in its favor include its noninvasive nature ("Laser is a less invasive treatment than surgery; I think it is worth promoting in China" [MD3]), safety ("I think SLT is worth popularizing because it can replace drugs [because it] has fewer side effects . . . SLT is also an option if the patient is unwilling to undergo surgery" [MD5]) and repeatability ("I think the best thing about it [SLT] is that it's noninvasive and then repeatable" [MD8]).
However, several physicians hold negative views about SLT. A key reason for this is that most physicians (n = 9, 82%) indicated that POAG, the type of glaucoma most suitable for SLT treatment, accounted for only 30-40% of patients in clinic. Physicians cited lack of evidence of the efficacy of SLT as a barrier to its use in the glaucoma treatment paradigm ("There's not a lot of evidence-based support [for using SLT] so we doctor generally just try it [but] not as a large, extensive treatment." [MD4]). Second, many hospitals do not have the equipment to do SLT ("The lack of equipment is part of the problem as not many hospitals in China have SLT machines . . . The price may be a reason. The LPI machine costs about 300,000 yuan whereas the SLT equipment in our hospital cost about 1.2 million yuan. We can't even recover the cost of the SLT machine" [MD1]). Third, the efficacy and effective duration of SLT do not always meet patient expectations ("Some physicians think that SLT only slightly controls IOP -that it results in a small reduction in IOP and then IOP elevates later. So they think patients will complain." [MD1]).
Physicians provided some suggestions on how to increase the use of SLT in China. First, laser treatment centers should be established in more hospitals: Second, SLT machines that are simpler to operate could help lower barriers to their use ("Lowering the difficulty of mastering SLT can promote its use." [MD3]). However, this is a debatable point given that other physicians did not think this was an issue ("SLT is relatively easy to master because it is actually similar to gonioscopy. Generally, physicians with certain qualifications can master it after simple training" [MD9]).

Discussion
Since 1995, when Latina and colleagues introduced SLT as a glaucoma treatment option, 3 there have been many studies on its efficacy and cost effectiveness. [4][5][6][7] Nonetheless, its clinical application is still relatively low in China. To our knowledge, this is the first study using qualitative data to understand the reasons behind the low acceptance of SLT, and to explore options to address barriers to its uptake in settings such as China as a first-line treatment.
In China, the overall prevalence of primary openangle glaucoma is less than that of primary closedangle glaucoma (1.02% and 1.40%, respectively). 17 In our study, physicians indicated that open-angle glaucoma accounts for only some 30% of cases seen in their clinics, likely due to the disease's insidious onset, making a timely diagnosis difficult. This is consistent with findings from the Singapore Epidemiology of Eye Disease Study. 18 The relatively small number of such patients in Chinese clinics may be an obstacle to the wider promotion of SLT. Although some recent studies have proved that SLT is also effective for treating angleclosure glaucoma, 19,20 physicians still regard open-angle glaucoma as the main type of glaucoma appropriate for treatment with SLT.
The physicians interviewed in this study indicated their treatment recommendations followed both Chinese and international guidelines. [8][9][10] The majority stated that topical medication is their first choice in treating early glaucoma, with treatment outcomes being highly dependent on patient compliance 21,22 and is often sub-optimal. 23,24 Yet according to official guidelines 8-10 and published trials, 5-7 SLT has been found to be non-inferior to medication in IOP reduction for selected glaucoma patients. In our study, only two physicians followed this recommendation. Incisional surgery, rather than SLT, was seen as more appropriate and acceptable when medications failed to control IOP because Chinese patients prioritized certainty and longevity of the intervention, even if it meant more drastic measures. 25 A key factor motivating patients to accept treatment for glaucoma was the presence of symptoms such as pain and visual loss affecting activities of daily living. 26,27 However, such symptoms are very unlikely to be present in early glaucoma, when SLT has shown to be most effective in preventing vision loss, which leads to a limited window of time to prove its benefit.
A willingness-to-pay analysis among glaucoma physicians confirms that physicians and patients have similar preferences for topical medications over SLT in early glaucoma for financial reasons. 28 Physicians' perceptions also affect the rate at which SLT is used in China. Although reliable studies have verified the effectiveness, safety and cost-effectiveness of SLT, 4-7 many physicians in our study believed it has poor treatment efficacy and short-term effectiveness based on their clinical experiences. Therefore, they expressed doubt SLT would meet patients' high expectations for treatment success. This barrier could be overcome by more widely sharing evidence-based research and existing SLT treatment guidelines with physicians in China, improving their understanding of its effectiveness.
Physicians in our study provided additional suggestions on how to promote the use of SLT in China, including establishing laser treatment centers in more geographically accessible hospitals, and developing new instruments to reduce the learning curve for SLT. In fact, such approaches are currently under development. 29 This view is also consistent with the model currently being explored in the United Kingdom, where optometrists are being trained to perform SLT treatment. 30 Education is one of the two keys to increase the use of SLT as an initial treatment for glaucoma in China. This includes ensuring that physicians are aware of existing guidelines and evidence-based research promoting this treatment. Providing evidence of SLT's efficacy and safety to patients can also increase the selection of this treatment. The second path would be to ensure more clinics outside of the major metropolitan areas in China can provide SLT. This entails training more physicians and providing the necessary equipment in clinics closer to patients living in rural areas, reducing travel time and costs.
This study is the first qualitative investigation conducted to better understand the reasons behind low uptake of SLT to control IOP in glaucoma patients, and to identify barriers to its uptake as a first-line treatment for glaucoma in China. Data were collected from both physicians and patients, which identified several overlapping factors associated with the choice of clinical treatment. Previous studies mainly focused either on specialist practice preferences or factors that influence patients' treatment compliance. 26,27,31,32 Including the views of both participant groups in this study strengthens confidence that our findings are broadbased and widely applicable.
There are limitations to this study. First, as is the norm with qualitative studies, findings should not be generalizable to a wider population because of the small sample size and non-random sampling method. Instead, the aim was to deeply explore factors affecting physician and patient preferences for treating glaucoma with SLT, a previously under-explored issue. Further studies that survey larger, randomly selected samples of physicians and patients would allow researchers to identify which factors are most influential in the choice of treatments to control IOP, and how best to overcome barriers to the wider use of SLT.

Disclosure statement
No potential conflict of interest was reported by the author(s).