Effective cataract surgical and refractive error coverages in the State of Qatar

doi:10.21203/rs.3.rs-4893781/v1

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Effective cataract surgical and refractive error coverages in the State of Qatar

https://doi.org/10.21203/rs.3.rs-4893781/v1

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Purpose

To evaluate the progress in Qatar's eye care since 2009, focusing on effective cataract surgical and refractive error coverages, leading to enhance eye health strategies and action plans.

Methods

A modified Rapid Assessment of Avoidable Blindness (RAAB) survey was employed using multi-stage sampling in all persons 50 years and older in Qatar. The study focused on uncorrected refractive errors, cataract surgery coverage and effectiveness, and visual acuity assessment, with secure data gathering.

Results

There were 339 individuals out of 3,206 examined participants who underwent cataract surgery out of which 66.1% of the operated eyes obtained ‘Good’ post-operative outcomes (Vision ≥ 6/12). The Effective Cataract Surgical Coverage (eCSC) was 61.2%, which is on par with developed countries. WHO set a global target for countries to achieve a 30 percentage-point increase in eCSC by 2030, accordingly Qatar's target should be 91.2% by 2030. Additionally, the study found that the Refractive Error Coverage and the effective Refractive Coverage across were 77.8% and 74.3%, respectively. Notably, these rates were lowest among Qatari women.

Conclusion

Qatar's eye care services have shown an improvement since the 2009 RAAB, with disparities in outcomes based on gender and nationality. Continued efforts are needed to meet WHO standards and reduce quality gaps, particularly among Qataris.

Qatar

Eye Health

Cataract Surgery

Refractive Error

Visual Acuity

Globally there are more than 400 million with vision impairment (VI),[1] mostly related to uncorrected refractive errors (URE) and untreated cataract contributing to 123.7 million and 65.2 million, respectively.[2, 3] In 2020,[4] the World Health Organization (WHO) in its 73rd World Health Assembly urged member countries to implement the recommendations in the World report on vision,[2] which included 1) the conduction of periodic population surveys to estimate the VI, 2) integration of variables relevant to eye care in general health surveys, and 3) reporting the effective coverage of cataract surgery and refractive errors.[4] Subsequently in 2021, member states at the 74th WHA endorsed the use of effective cataract surgical coverage (eCSC) and effective refractive error coverage (eREC) as indicators to measure countries’ progress in eye care as part of universal health coverage.[4, 5] Furthermore, the United Nations in its 2022 meeting identified these indicators as candidate indicators to measure the progress in the achievements of the components of the 2030 United Nations Sustainable Development Goals (SDGs).[5, 6] Healthcare governance in Qatar is exercised through Ministry of Public Health (MOPH), it supervises the country’s two principal health care providers: Hamad Medical Corporation (HMC) and Primary Health Care Corporation (PHCC).[7] Eye care services are mostly provided via HMC, the only public sector provider of cataract operations, and ophthalmic sub-specialty services, in addition to few private hospitals that offer the cataract operations services.[8, 9] In 2009, Qatar conducted a Rapid assessment of avoidable blindness (RAAB) study, revealing 1.28% of blindness prevalence; URE and cataract caused 42% and 33% of VI, respectively. Cataract surgical coverage (CSC) across the population was 68.2%.[10] RAAB is a population based cross-sectional survey with a standardized study design, procedures, mobile data collection and analysis via a digital application platform.[11] To track the country's eye care progress since the last RAAB study, including on cataract and RE service coverage, the MOPH and PHCC conducted a cross-sectional study using the RAAB7 methodology.

The RAAB survey was conducted across the state of Qatar from May to September 2022 and March to June 2023. A minimum sample size of 5060 was calculated using the RAAB sample size calculator, based on a 1.28% blindness prevalence from the 2009 RAAB study, with goals of achieving 0.4% precision and a 95% confidence level, factoring in a design effect of 1.4 and 10% non-response rate. Participants were selected using a stratified two-stage cluster random sampling, during the first stage, communities were used as primary sampling units (PSUs) and stratified into Qatari, and non-Qatari. The selection was divided proportionally between Qataris and non-Qataris in a 1:2.5 ratio; thus, out of 145 PSUs required for the study, 100 PSUs were assigned to the predominantly non-Qatari communities and 45 PSUs to the predominately Qatari communities. For each stratum, the number of PSUs was randomly selected from the strata’s PSUs with probability proportional to population size (PPS). The second stage was different from a typical RAAB sampling approach, here the Qatari planning and statistics authority utilized the population demographics to generate random numbers.[12] The 35 eligible persons, residing in a chosen PSU were randomly selected from an individual-level list of residents. The following Individuals were excluded 1) less than 50 years old, 2) resided in Qatar for less than six months, (visitors/ short contact workers), or 3) had contact with persons who had COVID-19 confirmed infection. A certified trainer nominated by the LSHTM trained 10 teams (each with an ophthalmologist and 2 nurses) on the survey design, data entry, and examination protocols. The training done in two batches aimed for Kappa coefficients above 0.60 for Inter-Observer Variation accuracy for VA, lens assessment, and causes of vision loss. Each selected survey participant was contacted by phone to seek his/her consent and then booked to attend one of 10 health centers selected for the survey. Upon arrival at the health center, participants confirmed their identity and consented to participate in the study in writing. Using the RAAB7 Android application on tablets, data was entered, including examination results and medical history. All participants underwent VA measurement (uncorrected, corrected, pinhole) deploying the Peek Vision acuity test,[13] in the RAAB7 application. Lens was assessed by an ophthalmologist to determine the presence of aphakia, pseudophakia, or lens opacity. Any participant with a presenting VA (PVA) of < 6/12 in any eye was further assessed by an ophthalmologist to determine the cause of poor vision with pupil dilatation where needed. The study obtained ethical approval from the MOPH. Data were recorded on encrypted, password-protected mobile data collection devices, each equipped with GPS to log the location of survey completion, followed by a secure upload directly to Peek Vision's encrypted server. Access to the data was limited to the Principal Investigator (PI), RAAB trainer, and selected Peek technical staff. After the survey, identifiable data were removed. The RAAB methodology followed a WHO algorithm for determining the main cause(s) of vision impairment for eyes and person.[14] All Vision impairment was defined as combination of all levels of vision impairment excluding the blindness, i.e., as a combination of mild, moderate, and severe VI. Mild VI = PVA < 6/12 but ≥ 6/18, Moderate VI = PVA < 6/18 but ≥ 6/60 and Severe VI = PVA < 6/60 but ≥ 3/60 in the better eye. Blindness was defined as a PVA is less than 3/60 in the better eye.[14] Cataract surgical coverage (CSC) and eCSC are indicators to capture the extent of cataract surgery reach,[15, 16] eCSC reflects the proportion of adults who need cataract surgery, have undergone the operation, and achieved a good level of distance VA. [15, 16]

CSC = (X + Y) / (X + Y + Z).

eCSC = (A + B) / (X + Y + Z)

A = Individuals with unilateral cataract surgery achieving post-operative VA ≥ 6/12 in the operated eye with pinhole VA < 6/12 in the other eye.
B = Individuals with bilateral cataract surgery achieving post-operative VA ≥ 6/12 in at least one eye.
X = Individuals with unilateral cataract surgery + pinhole VA < 6/12 in the other eye
Y = Individuals with bilateral cataract surgery (regardless of VA).
Z = Individuals with pinhole VA < 6/12 in both eyes as cataract is the primary cause of visual impairment.

The relative quality gap (difference between eCSC and CSC) was calculated as (CSC–eCSC)/CSC, with lower values reflecting better quality of cataract surgical services. Other indicators were Refractive Error Coverage (REC) and eREC, the latter measures the proportion of individuals who need and receive the refraction services, improving their uncorrected VA (UCVA) from worse than 6/12 to 6/12 or better. The RAAB7 methodology defines the presence of URE, as VA of < 6/12 in the better eye that could be improved to equal to or better than 6/12 by refraction (corrected VA, CVA), or by placing a pinhole occluder in front of an eye (pinhole VA, PinVA).[16–18]

REC = (A + B) / (A + B + C)

eREC) = A / (A + B + C).

A = Individuals with spectacles, or contact lenses, whose UCVA = < 6/12 in the better eye achieving CVA = 6/12 in the better eye (Met Need).
B = Individuals with spectacles, or contact lenses, whose UCVA and CVA are < 6/12 in the better eye but improved to 6/12 or better with Pinhole (Undermet Need).
C = Individuals with no spectacles, nor contact lenses, whose UCVA < 6/12 in the better eye, and PinVA is 6/12 or better in the better eye (Unmet Need).

Out of the target sample size of 5060, 4064 (80.3%) participants were enrolled in the survey, among those enrolled, 3206 people were examined, (59% were males and 35% were Qataris), a response rate of 78.9%. The prevalence of bilateral blindness was (0.4%, 95%CI 0.2–0.7), mild VI (5.2%; 95%CI 4.3–6.1), moderate VI (3.81%; 95%CI 3.0-4.5), and severe VI (0.3%; 95%CI 0.1–0.5).The main causes of blindness were diabetic retinopathy (33.3%), cataract (20%), and glaucoma (13%), while the main causes of All VI were URE (58%), cataract (17%), and DR (7%), (Table 1). Data on the prevalence of bilateral cataracts based on the VA threshold for surgical intervention offers valuable insights when the pinhole VA threshold exceeds 6/18, the age-sex adjusted prevalence of bilateral cataracts was 0.4% (CI: 0.1% − 0.6%) but lowering the pinhole VA threshold to 6/12 leads to an age-sex adjusted prevalence of bilateral cataract of 1.1% (CI: 0.7% − 1.6%), Table 2. This represents 1,847 individuals in Qatar who suffer from bilateral cataract, Qataris (2.4%), non-Qatari (0.6%), women (1.6%), and men (1%). There were 559 eyes from 339 individuals who received cataract surgery. A post-operative Good outcome VA (PVA of 6/12 or better) was achieved in 66.1% of all operated eyes: Qataris (58.3%), non-Qataris (73.9%) Males (70.5%), and females (60.9%). Poor post-operative vision was 9.3% of all operated eyes (Table 3). The age and sex-adjusted CSC for cataract surgical threshold of VA < 6/12 across the overall population was 85.6% (95% CI 81.1-90.04), while the age and sex-adjusted eCSC for post-operative vision of ≥ 6/12 on cataract surgical threshold of < 6/12 for the overall population was 61.2% (95%CI 54.9–67.4), with higher rates in males and non-Qataris. These indicator values were higher for lower surgical thresholds, the CSC and eCSC were 98.6% and 72.4% respectively for surgical threshold of 6/60. Table 4 shows the adjusted CSC and eCSC at Person level for Good surgical outcome of PVA of 6/12. The causes of poor post-operative vision outcomes were ocular comorbidity (50.9%), surgical complications (31.5%), and URE (17.6%). The relative quality gap, a measure of difference between CSC and eCSC, with lower values reflecting better quality, was 37.8% in Qataris, 18.6% in non-Qataris, 23.1% in males and 34.7% in females. Over 77% of the participants had no need for distance refractive correction. Among the 22.6% in need of glasses, 16.8% had the correct prescription (met need), 5% had no refractive correction at all (unmet need) and 0.8% had suboptimal correction (undermet need). Table 5 shows the age and sex-adjusted REC and eREC across the population, they were 77.8% (95%CI 74.5–81.0) and 74.3% (95%CI 70.9–77.7), respectively, with both being lower among Qatari women. Accordingly, the Relative Quality Gap for refractive error coverage was wider among the Qataris compared to non-Qataris (6.4% vs 3.8%) and women to men (5.1% vs 3.6%). Over a third of the participants reported using distance glasses, and over two-thirds used reading glasses. Notably, using distance and reading glasses was more common among non-Qatari and males. (Table 6).

Table 1

Percentage of main causes of all vision impairment by nationality
Causes	Qatari		Non-Qatari		Total Sampled
Causes	%	Number	%	Number	%	Number
Uncorrected refractive error	48	89	71	96	58	185
Cataract	21	38	13	18	17	56
Diabetic retinopathy	8	15	4	6	7	21
Other posterior segment diseases	5	9	4	6	5	15
Corneal opacity	4	8	3	4	4	12
Globe/ Brain diseases	5	9	1	2	3	11
Age related macular degeneration	4	8	2	3	3	11
Cataract surgery complications	3	5	0.7	1	2	6
Glaucoma	1.1	2	0	0	0.6	2
Trachoma	0.5	1	0	0	0.3	1
Phthisis	0.5	1	0	0	0.3	1
Total	100	185	100	136	100	321

Table 2

Adjusted prevalence of bilateral cataract by nationality and gender
No.	Bilateral cataract	Qatari % (95%CI)	Non-Qatari% (95%CI)	Male% (95%CI)	Female% (95%CI)	Total% (95%CI)
1	Pinhole VA < 6/12	2.4 (1.3–3.4)	0.6 (0.2–0.9)	1.0 (0.5–1.4)	1.6 (0.8–2.3)	1.1 (0.7–1.6)
2	Pinhole VA < 6/18	0.8 (0.3–1.3)	0.2 (0.0-0.4)	0.3 (0.0-0.6)	0.5 (0.1–0.8)	0.4 (0.1–0.6)
3	Pinhole VA < 6/60	0.1 (0.0-0.3)	0.0 (0.0-0.1)	0.0 (0.0-0.1)	0.1 (0.0-0.2)	0.1 (0.0-0.1)

Table 3

Post-operative Presenting VA of eyes by nationality and gender
No.	Presenting VA outcome	Qatari %	Non-Qatari%	Male%	Female%	Total%
1	Good (6/12)	58.3	73.9	70.5	60.9	66.1
2	Borderline (< 6/12 − 6/60)	29.9	19.4	21.4	28.5	24.6
3	Poor (< 6/60)	11.9	6.4	8.1	10.7	9.3

Table 4

Adjusted cataract surgical coverage and effective cataract surgical coverage at the person level
CSC/eCSC	Nationality		Sex		Total	Relative quality Gap (%)
	Qatari	Non-Qatari	Males	Females	Total
	Prev % (95%CI)	Prev % (95%CI)	Prev % (95%CI)	Prev (95%CI)	Prev (95%CI)
Cataract surgical threshold Pinhole VA < 6/12
CSC	83.5 (76.5–90.6)	88.9 (83.8–94)	87.8 (82.7–92.8)	83.2 (76.6–89.8)	85.6 (81.1–90.0)	28.5
eCSC	52.0 (42.8–61.2)	72.4 (64.8–79.9)	67.5 (59.8–75.2)	54.3 (46.3–62.9)	61.2 (54.9–67.4)
Relative quality gap (%)	37.8	18.6	23.1	34.7	28.5
Cataract surgical threshold Pinhole VA < 6/18
CSC	93.3 (88.9–97.8)	95.4 (92.2–98.7)	95.4 (91.6–99.2)	93.3 (88.9–97.6)	94.4 (91.7–97.2)	27.7
eCSC	58.5 (48.7–68.3)	78.6 (71.6–85.5)	72.7 (65.1–80.4)	63.0 (54.7–71.3)	68.3 (62.0–74.5)	27.7
Cataract surgical threshold Pinhole VA < 6/60
CSC	98.5 (96.2–100)	99.5 (97.9–100.0)	99.3 (97.9–100.0)	97.8 (95.3–100.0)	98.6 (97.3–100.0)	26.6
eCSC	62.3 (52.3–72.7	83.1 (76.8–89.5)	76.3 69.1–83.4	67.6 (59.2–76.1)	72.4 (66.2–78.5)	26.6
Prev = Prevalence, CSC = cataract surgical coverage, eCSC = effective cataract surgical coverage

Table 5

Age and sex adjusted refractive error coverages.
REC and eREC*	Qataris %			Non-Qataris %			Total %
REC and eREC*	Males	Females	Total	Males	Females	Total	Males	Females	Total
REC	72.2	58.9	66.6	85.7	82.6	84.2	83.1	72.9	77.8
eREC	67.5	55.3	62.3	83.0	85.7	81.0	80.1	69.2	74.3
Relative Quality Gap			6.4			3.8	3.6	5.1	4.4
REC: Refractive error coverage; eREC: effective Refractive error coverage

Table 6

Sample prevalence of spectacle use among Qataris and Non-Qataris
Spectacles Use	Qataris %			Non-Qataris %			Total %
Spectacles Use	Males	Females	Total	Males	Females	Total	Males	Females	Total
Distance Spectacles	33.8	24.2	28.5	41.7	40.7	41.4	39.6	32.9	36.8
Near Spectacles	64.4	62.3	63.3	74	71	73	71.5	66.9	69.6

The RAAB study in Qatar estimated that over 91% of population aged 50 + years exhibited a VA better than 6/12. Because of the younger age of non-Qatari stratum, they had a higher predisposition of URE causing VI, whereas the more elderly Qatari strata was more afflicted with the age-related cataract. Because Qataris were older with likelihood of having other chronic eye diseases, they obtained less favorable outcomes of cataract surgery, as 50.9% of poor post-operative vision was due to co-morbidities. The WHO recommends attainment of post-operative presenting vision of 6/12 or better in at least 80% for all operated eyes as the benchmark for a "Good outcome" to successful cataract operation.[15, 18] The Good outcome was achieved in 66.1% of operated eyes in the study, which was similar to Taif, Saudi Arabia (62%) and Mexico (61%) but higher than Armenia (53.1%).[19, 20] Although the definition of good outcome for the Saudi Arabian and Mexican studies were based on VA > 6/18 in contrast to our study that had higher threshold of VA > 6/12. The poor post-operative vision was 9.3% of the operated eyes exceeding the WHO's recommended maximum of 5%,[21, 22] yet still lower than in Taif, Saudi Arabia (19%) or Mexico (21%).[19, 23] The CSC was notable at 85.6% for cataract of VA < 6/12 and 94.4% for cataract of VA < 6/18, comparing the latter to previous studies: Qatar RAAB 2009 (68.2%), Armenia (69.5%), Sichuan-China (65.6%), Oman (61%), and Malaysia (47.5%).[10, 20, 24–26] These figures highlight the significant improvement in coverage of cataract services in Qatar over the last decade. The eCSC which estimates proportion of cataract cases that have had satisfactory visual results following cataract surgery, was 61.2 (95%CI 54.9–67.4) more in males and non-Qataris. It is in line with higher-income nations' average (60.5%),[15] but it falls short of Hungary, which reports 70.3%.[27] WHO set a global target to achieve a 30 percentage-point increase in eCSC by 2030, accordingly Qatar's target should be 91.2% by 2030.[4] Such an outcome would need to be addressed by eye care providers in Qatar to reduce the coverage and quality disparities, as the quality gap is higher in Qataris than non-Qataris (37.8% vs 18.6%). The distance eREC was 74.3%, (95%CI 70.9–77.7) showing disparities based on gender and nationality (higher in males and non-Qataris), but it outperforms the global average (42.9%), North Africa (62.1%),and Middle East (54.7%), placing Qatar among the high-income nations with an eREC of 79.1% (95% CI 72.4–85.0), only 4.8% behind the top rate.[28, 29] The study might have overestimated the number of participants who used distance glasses as some participants could have reported the use of reading glasses or sunglasses as distance glasses. Also, participants might have reported using distance glasses that improve their vision from 6/12 or 6/9 to 6/9 or 6/6 respectively, which was not counted in RAAB methodology as refractive error because of the definition used. The refractive error services need to be improved especially to cover the demographics that demonstrated lower coverage, i.e. Qataris and women. Almost 70% of the participants wore reading glasses, aligning with global trends that presbyopia affects five times more than distance vision impairment.[29] Although the response rate of the study was less than optimal, the sample represented the study population as the proportion of males and Qatari nationals examined reflected the proportion for the same age group in the total population. The study faced limitations due to the less-than-optimal response rate that was related to the participants’ recruitment and inviting them to their health centers instead of using the typical door-door approach in RAAB studies. It notes that 20% of the selected sample were unreachable by telephone, and 20% declined participation, citing reasons such as disinterest or prior/ future appointments with their ophthalmologist. These challenges are pronounced in high-income countries with excellent access to eye health care services resulting in insufficient sample sizes for the two distinct strata—Qatari and non-Qatari. Eventually, it compromised the precision for subgroup estimates, which should be interpreted with caution. To fully leverage the survey results, an Eye Care Service Assessment Tool (ECSAT) is advised, paving the way for tailored recommendations to improve eye care in Qatar as well as services quality assessment tools such as Cataract BOOST or the UK NOD Cataract audit system.[30, 31] In conclusion, the RAAB survey highlighted Qatar's significant strides in eye care, with notable achievements in cataract surgical Coverage and effective refractive error correction, surpassing global averages. However, it was revealed that women had reduced access to cataract surgery and refraction services. Consequently, to align with the WHO objective of achieving universal coverage (100%), Qatar is needs to improve cataract coverage using evidence- based tools.

Acknowledgement

We extend our gratitude to Dr. Badria Al Malki for her invaluable contributions. Dr. Al Malki, who unfortunately passed away shortly after completing the survey, played a pivotal role as the national coordinator for blindness prevention in Qatar, providing logistical support and overseeing field activities. We appreciate the generous involvement in the project by the London School of Hygiene & Tropical Medicine and Peek Vision for their expertise in RAAB training and the implementation of RAAB7 methodology. We must acknowledge the dedication of the field team, consisting of ophthalmologists and nurses who meticulously gathered data and conducted participant examinations efficiently. Finally, we greatly appreciate the survey participants for consenting to participate in the study.

Statement of Ethics

The study received ethical approval from the ethical committee of Primary health care corporation. Qatar (Ref. PHCC/DCR/2022/04/023). While the majority of participants provided written consent during their visits to health centers, 7 participants were severely ill and bedridden. These participants were chosen randomly, and their legal guardians accepted their participation in the study, signing the consent forms during home visits.

Conflict of Interest Statement

None of the authors have any proprietary interests or conflicts of interest related to this submission.

Funding Sources

The survey was funded by Qatar Ministry of Public Health and publishing fees was paid by Qatar national library. The funding sources had no influence on study design, conduct, analysis, or reporting. The manuscript has not been published anywhere previously.

Author Contributions

Al Ashwal S: Writing- Reviewing, Software, Investigation and Editing. Rabiu M: Writing- Original draft preparation, Conceptualization, and Methodology. Mccormick: I Writing- Original draft preparation, and Data curation. Al Qahtani O, Funding, and Supervision Salih H: writing- Reviewing, Validation and Supervision. Kokuu S: Visualization, Software, and administrative support. AlThani M: funding, writing- Reviewing, and Editing.

Data Availability Statement.

Data supporting the findings of this study are available from the corresponding author upon reasonable request. Restrictions apply to the availability of these data due to privacy or ethical concerns.

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No competing interests reported.

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Effective cataract surgical and refractive error coverages in the State of Qatar

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Abstract

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Introduction

Materials and Methods

REC = (A + B) / (A + B + C)

Results

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