Early Patching Behaviors that Improve the Chances of Good Visual Acuity in Children Treated for Unilateral Congenital Cataract

Abstract

Objective:

Achieving near normal vision following unilateral congenital cataract surgery is possible but requires early surgery, optical correction and consistent patching. Patching is often challenging for children and their caregivers. The goal of these analyses is to examine the association between reported consistency in patching during the first year after surgery and visual acuity.

Design:

Data from the Infant Aphakia Treatment Study (IATS) are used in a cohort design.

Participants:

101 children whose caregivers completed a prospective, 7-day patching diary two months after surgery or at 13 months of age.

Methods:

Consistent patching was defined as patching every day, and either an average patch start time before 9:00 am, or the interquartile range of the first time a patch was applied of 60 minutes or less.

Main Outcome Measures:

Recognition visual acuity was assessed at ages 54 + 1 months and 10½ years. Near normal visual acuity was defined as visual acuity of 20/40 or better.

Results:

Diary data were available for 101 children. Overall, 55% of children whose caregivers reported consistent patching at age 13 months had near normal vision at age 54+1 months and 45% had near normal vision at age 10.5 years compared to 14% and 18%, respectively, when caregivers reported less consistent patching (Relative risk 54 months of age 3.55, 95% CI 1.61,7.80; RR at 10.5 years of age 2.31, 95% CI 1.12,4.78).

Conclusion:

Consistent patching in the first year following surgery for unilateral congenital cataract is associated with better visual acuity. These findings can be used to provide evidence-based guidance to caregivers to help improve visual acuity outcomes for their children.

Precis:

Children born with a unilateral congenital cataract whose caregivers report patching every day around the same time each day have better visual outcomes than those whose caregivers reported less consistent patching routines.

Introduction:

Vision rehabilitation in children with a unilateral Congenital Cataract (UCC) is one of the most difficult problems in pediatric ophthalmology. Until the 1970’s, UCC was believed to invariably result in poor vision for all affected children. Since then, good visual outcomes have been reported in some eyes.^1–5 However, good visual outcomes are not guaranteed; for example, only 20% of treated eyes in the Infant Aphakia Treatment Study (IATS) achieved a visual acuity (VA) of 20/40 or better,^6,7 and relatively few children demonstrated stereopsis.^8,9

Three primary factors have been associated with achieving good visual acuity: early removal of the cataract, consistent optical correction and part-time patching of the fellow eye, throughout the amblyogenic period (up to 7 to 9 years of age).¹⁰ However, poor adherence to prescribed patching is a significant impediment to the successful treatment of UCC and most studies report that parents of children with UCCs and, even those with amblyopia from other causes, achieve less than half of the patching prescribed for their children.^11–13 Parents report difficulties maintaining the patching regimen,^14,15 that patching can be stressful,^16–18 that adherence to prescribed patching is negatively impacted by their lack of understanding of evidence that occlusion therapy benefits their children, and by the adverse impact of patching on their children’s behavior and on family relationships.^17,19,20

For patients with UCCs, patching in infancy has been shown to be more strongly associated with good visual outcomes than patching during the toddler and/or preschool years, particularly after patching in infancy is considered.¹³ This is likely because early patching helps establish patching routines for both children and caregivers, allows the child to become accustomed to wearing the patch, and facilitates development of good visual acuity, which may reduce resistance to future patching.¹⁴ During the first year of life, adhering to prescribed patching is entirely dependent on the caregiver. Thus, assuring families of the value of patching, and providing them with guidance on ways to achieve the prescribed patching regimen is important for optimizing outcomes in children with UCC.²¹

A variety of strategies, including caregiver education programs^22–24 to enhance adherence to medical routines, such as patching for amblyopia, have been proposed.^25,26 However, much of this research is focused on older children for whom the predictors of adherence are likely to differ from those relevant in infancy²⁷ and the proposed solutions are often not applicable to this age group.²⁸ Further, adherence during early life depends more on the caregiver’s than on the child’s behaviors, unlike in later childhood when the child may object to wearing a patch.

Based on the health belief model, caregivers are most likely to comply if they understand and are convinced of the necessity as well as the benefit of adhering to prescribed patching. Additionally, pairing treatment tasks with regularly occurring events²⁹ and providing external reminders or cues are effective in improving adherence to prescribed regimens for other pediatric conditions.^30,31 Thus, establishing a patching habit based on external cues, such as time of day or morning waking, should improve adherence to prescribed patching. We hypothesize that patching every day, at about the same time, and/or first thing in the morning are likely to improve adherence to prescribed patching and thereby improve the chances that a child will obtain good vision.

Methods:

These post hoc analyses leverage data from the Infant Aphakia Treatment Study (IATS),^6.7 a multi-center, randomized controlled clinical trial of treatment for UCC. The primary objectives of the original study were to compare visual and adverse outcomes in children receiving an intraocular lens (IOL) at the time of cataract extraction relative to those left aphakic and wearing a contact lens for refractive correction. Written informed consent from caregivers was obtained, and children provided assent at age 10.5 years. The study was approved by the institutional review boards of all participating institutions and was in accordance with the tenets of the Declaration of Helsinki. The clinical trials identifier is: NCT00212134

Visual Acuity:

We selected visual acuity in the treated eye as the primary outcome for these analyses since that has been the primary goal of treatment for unilateral congenital cataracts. Monocular recognition acuity was assessed by a traveling tester at 54 +1 months of age using the Amblyopia Treatment Study-HOTV protocol.^32,33 At age 10.5 years, a clinical staff member, who had been trained in the study protocol, assessed acuity using the E-ETDRS testing protocol.^34–36 Additional details about the visual acuity testing at these ages have previously been reported.^6,7,32

For the current analyses, visual acuity in the treated eye was analyzed in two ways: as a continuous variable using logMAR acuity, and as a dichotomous variable comparing those with near normal vision (visual acuity of 20/40 or better, logMAR ≤ 0.30) to all other outcomes. This dichotomy was selected since a visual acuity of 20/40 would permit driving in all 50 states in the United States of America. Further, we have previously shown that a substantial proportion (22%) of children with visual acuity of 20/40 or are able to demonstrate some degree of stereopsis at age 10.5 years.³⁷

Patching:

Starting the second week after cataract extraction, caregivers were advised to have their child wear an adhesive occlusive patch over the fellow eye for one hour daily for each month of life until the child was 8 months of age. Thereafter, patching was prescribed for 50% of waking hours until age 5. Patches were provided at no cost to patients throughout this period. After age 5, clinicians prescribed patching based on their clinical judgement, and patching supplies were no longer provided to families.

Caregivers reported the amount of patching that a child received throughout the first five years of life in prospective patching diaries that covered 7 consecutive days. These diaries were mailed from the Data Coordinating Center (DCC) to the families two months after surgery and at 13-, 25-, 37- and 49-months of age (38 – Drews-botsch). The patching diaries provided information about all times that the child went to sleep, woke up, applied the patch and removed the patch. Caregivers also recorded each time the contact lens was put on and taken out and/or the glasses were put on and taken off.

For these analyses, we used this information to derive the consistency of patching reported on the first two diaries. Consistency was defined as patching every day and applying the patch for the first time each day around the same time. We defined patching around the same time as either (1) morning patching (i.e., the average of 1^st patch application being before 9:00 am) and/or (2) usually patching around the same time which was defined as the inter-quartile range (IQR or 50% of the first time the patch was applied) was 60 minutes or less. We developed measures of consistent patching for the diary completed two-months after surgery, at age 13-months, and on both of these diaries combined.

Patching was also reported every three months on 48-hour recall interviews. These interviews were conducted by trained staff in the DCC. We estimated the average hours of patching prior to the child’s first birthday, and between 12- and 48-months of age by averaging the hours of patching that were reported on all interviews and diaries, combined, during these two periods.

Statistical Analysis:

Statistical analyses were conducted using SAS 9.4 (SAS, Cary, NC) and SPSS 29.0 (SPSS Inc., Arlington, VA). We conceive of these analyses as representing a cohort of children whose caregiver(s) completed a prospective 7-day patching diary two months after surgery and/or at 13-months of age. LogMAR visual acuity was considered a continuous variable. The association between dichotomous patching habits and mean visual acuity at 54-months and 10½ –years of age were evaluated using t-tests, and linear regression. Risk ratios were used to assess the likelihood of achieving near normal visual acuity in the treated eye at 54-months and 10½ years of age by early patching habits. All P values were two-sided and not adjusted for multiple analyses as our primary purpose was to estimate the size of the effect and because all of our analyses represented a priori hypothesized associations.

Results:

The IATS enrolled 114 children who were randomly assigned to either receive an intraocular lens (IOL) at the time of cataract extraction or to remain aphakic. We excluded three children who had severe complications and were left with extremely poor visual acuity in the treated eye given that patching was unlikely to provide benefit to them. The current analyses include the 105 children who participated in the IATS and whose caregiver(s) completed either a 7-day patching diary 2 months after surgery and/or at 13-months of age: 99 caregiver(s) completed diaries two months after surgery and 86 caregiver(s) completed diaries at 13-months of age. Of these, 101 had visual acuity successfully measured at 54 months of age and 96 at 10½ years of age. More than three-quarters of the children whose caregiver(s) completed one or more diaries and who had visual acuity data, had complete data available for all 14 possible diary days (Table 1).

Table 1:

Number of days of diary data available for those with visual acuity measured at 54+1 months or 10.5 years of age

DAYS OF RECORDED PATCHING	VISION MEASURED AT 54 MONTHS OF AGE	VISION MEASURED AT 10.5 YEARS
0 1	10	9
6	1	1
7	20	19
11	1	1
13	2	2
14	75 (75.8%)	73 (76.0%)

¹Excluded from analyses because of the lack of data

As expected, based on earlier analyses, whether a child received an IOL or a contact lens was not associated with visual acuity, but visual acuity outcomes were associated with having access to private insurance as a proxy for socioeconomic status and access to healthcare, and age at surgery Ttable 2). In identifying confounding variables, we assessed the relationship between reported patching habits and whether the child received an IOL at the time of cataract extraction, private insurance and age at surgery. We also considered whether the age that the 1^st diary was completed was associated with patching habits given the age ranges of the patients at time of surgery.

Table 2:

Association between Possible Confounders and Good Visual Acuity in IATS participants at 54 months and 10.5 years of age

VARIABLE	VISUAL ACUITY AT 54 MONTHS OF AGE			VISUAL ACUITY AT 10.5 YEARS OF AGE
	≤ 20/40	>20/40	RR (95% CI)	≤ 20/40	>20/40	RR (95% CI)
TREATMENT
CL	17	38	1.28 (0.68,2.38)	14	38	1.19 (0.61,2.32)
IOL	13	41		12	41
INSURANCE
Private	24	44	2.41 (1.08,5.40)	19	46	1.67 (0.77,3.61)
Other	6	35		7	33
AGE AT SURGERY
≤48 Days	17	24	2.17 (1.18,3.99)	17	25	2.83 (1.40,5.75)
>48 Days	13	55		9	54
AGE AT 1st DIARY
3–4 months	20	38	Χ2=3.52, p=0.17	20	36	Χ2 = 7.45 p=0.02
5–7 months	4	23		2	24
8–9 months	3	68		2	8

Consistency in reported patching was associated with whether or not the family had access to private insurance (Table 3), but was not associated with whether or not a child received an IOL at the time of cataract surgery, with the age of the child at surgery or with the age the child was when the 1^st diary was completed. However, the age at surgery was associated with consistent patching as reported at 13-months of age, but not 2 months after surgery or overall.

Table 3:

The association between consistency in reported patching and potential confounding factors

			CONSISTENT patching1	LESS CONSISTENT PATCHING	Χ2	P-VALUE
BOTH DIARIES	Treatment	IOL	13	39	0.40	0.53
		Contact Lens	15	34
	Insurance	Private	23	41	5.88	0.02
		Other	5	32
	Age at Surgery	≤48 Days	13	28	0.55	0.46
		>48 Days	15	45	0.65	0.72
	Age at 1st Diary	3–4 months	18	41
		5–7 months	6	21
		8–9 months	3	7
1ST DIARY 2	Treatment	IOL	15	33	2.15	0.14
		Contact Lens	22	26
	Insurance	Private	30	32	7.16	<0.01
		Other	7	27
	Age at Surgery	≤48 Days	14	26	0.36	0.55
		>48 Days	J23	33
	Age at 1st Diary	3–4 months	20	39	1.49	0.48
		5–7 months	12	15
		8–9 months	5	5
2ND DIARY 3	Treatment	yOL	14	29	1.59	0.21
		Contact Lens	18	21
	Insurance	Private	26	31	3.41	0.06
		Other	6	19
	Age at Surgery	≤48 Days	18	16	4.73	0.03
		>48 Days	14	34

¹Reported patching every day either usually before 9:00 am or around the same time

²Completed 2 months after surgery

³Completed at 13 months of age

On average, children whose caregivers reported more consistent patching patterns had better visual acuity than those whose caregivers reported missing one or more days of patching or who reported patching on a less consistent schedule either often patching after 9:00 am or starting to patch at a variety of times throughout the day. For example, at 54 months of age, the average logMAR visual acuity among children whose caregivers who reported a consistent patching pattern on both diaries was 0.60 (95% CI 0.38,0.82) as compared to 1.14 (95% CI 0.96,1.33) among those for whom no patching was reported on at least one day, yielding a mean difference of 0.55 logMAR (95% CI 0.22,0.87) (Table 4, Figure 1). The results were similar for visual acuity measurements obtained at age 10½ years and for consistency in patching reported 2-months after surgery and at 13-months of age.

Table 4:

Mean Difference in Visual Acuity by Reported Patching Consistency

TIMING	CONSISTENT	VISUAL ACUITY AT 4.5 YEARS		VISUAL ACUITY AT 10.5 YEARS
		logMAR Acuity	Difference	logMAR Acuity	Difference
ALL DIARIES	Consistent1	0.60 (0.38,0.82)	0.55 (0.22,0.87)	0.61 (0.86,1.14)	0.39 (0.13,0.65)
	Less Consistent2	1.15 (0.96,1.33)		1.00 (0.86,1.14)
1st DIARY 3	Consistent	0.72 (0.53,0.92)	0.45 (0.16,0.74)	0.62 (0.38,0.86)	0.50 (0.18,0.81)
	Less Consistent	1.18 (0.95,1.40)		1.12 (0.91,1.33)
2nd DIARY 4	Consistent	0.62 (0.38,0.86)	0.50 (0.18,0.81)	0.57 (0.36,0.78)	0.45 (0.19,0.72)
	Less Consistent	1.12 (0.91,1.33)		1.02 (0.85,1.19)

¹Defined as patching every day and either 1^st applying the patch on average before 9:00 am and/or 1^st applying the patch within the same sixty-minute period 50% of the time.

²Either not patching daily or usually patching after 9:00 am and 1^st applying the patch at a variety of times.

³Completed 2 months after surgery

⁴Completed at 13 months of age

Figure 1:

Box plots of visual acuities at 54 months and 10.5 years of age by consistency in reported patching in the first year following surgery

Y-axis: logMAR Visual Acuity (median, interquartile range, minimum and maximum)

X-axis: Left Bar – children with less consistent patching; Right Bar – children patched every day either before 9:00 am or starting within the same hour.

Similarly, the probability of achieving nearly normal vision (i.e. a visual acuity of 20/40 or better) was higher in children whose caregiver(s) reported patching every day either before 9:00 am or around the same time each day on both diaries. Specifically, the probability that a child would have a visual acuity of 20/40 or better at 54 months was more than twice as high if the caregiver(s) reported patching every day, on average before 9:00 am or within the same hour than if a less consistent patching pattern was reported (RR = 2.13, 95% CI 1.15,3.95) (Table 5). This association was no longer statistically significant after adjusting for private insurance. However, for data from the diary completed at 13-months of age, the association between consistent patching and near normal vision at both 54 months and 10.5 years of age remained statistically significant, even after adjusting for private health insurance. The weaker association between consistency in patching reported on both diaries than that reported on the diary at 13-months of age is likely attributable to the lack of an association between consistency in patching reported 2-months after surgery because younger infants have a less consistent daily schedule making it more difficult to start patching at a consistent time of day.

Table 5:

Crude and adjusted¹ relative likelihood of achieving near normal vision² by reported consistency³ in patching behaviors

	VISUAL ACUITY AT 4.5 YEARS				VISUAL ACUITY AT AGE 10.5 YEARS
	20/40 or better	Worse than 20/40	Crude RR	Adjusted RR	20/40 or better	Worse than 20/40	Crude RR	Adjusted RR
	REPORTED ON BOTH DIARIES
Consistent	12	15	2.13 (1.15,3.95)	1.78 (0.84,3.35)	11	16	2.01 (1.05,3.86)	1.83 (0.92,3.63)
Less Consistent	15	57			14	55
REPORTED ON 1ST DIARY4
Consistent	13	24	1.46 (0.77,2.74)	1.18 (0.61,2.28)	9	26	0.98 (0.48,1.99)	0.81 (0.38,1.73)
Less Consistent	14	44			> 15	42
	REPORTED ON 2ND DIARY5
Consistent	17	14	3.92 (1.84,8.36)	3.55 (1.61,7.80)	14	17	2.41 (1.19,4.88)	2.31 (1.12,4.78)
Less Consistent	7	43			9	39

¹Adjusted for having private insurance

²Visual acuity of 20/40 or better

³Defined as patching every day and either usually starting patching before 9:00 am or usually patching around the same time each day

⁴Completed 2 months after surgery

⁵Completed at 13 months of age

The observed association between patching consistency and visual acuity may be attributable to patching consistency resulting in more total hours of patching being achieved, both within the first year following surgery and the subsequent years. Indeed, we found that children whose caregivers reported more consistent patching in the first year after surgery reported more average hours of patching, both during the 1^st year of life and for the subsequent three years (Table 6).

Table 6:

Mean hours of patching per day reported in the first year of life and between 12 and 48 months of life by patching every day either before 9:00 am or around the same time each day

TIMING	CONSISTENT	BEFORE 12-MONTHS OF AGE		BETWEEN 12 AND 48 MONTHS OF AGE
		Average daily hours of patching	Difference	Average daily hours patching	Difference
ALL DIARIES	Consistent	4.82 (4.30,5.35)	1.32 (0.63,2.02)	4.96 (5.43,5.48)	1.93 (1.12,2.73)
	Less Consistent	3.50 (3.12,3.89)		3.03 (2.57,3.49)
2-MONTHS AFTER SURGERY	Consistent	5.01 (4.59,5.42)	1.81 (1.21,2.41)	4.77 (4.23,5.32)	1.92 (1.15,2.68)
	Less Consistent	3.20 (2.79,3.60)		2.86 (2.35,3.37)
13-MONTHS OF AGE	Consistent	4.72 (4.23)	1.16 (0.48,1.383)	4.70 (4.12,5.29)	1.64 (0.82,2.46)
	Less Consistent	3.56 (3.11,4.02)		3.06 (2.51,3.62)

Discussion:

Our results suggest that patching consistently, every day in the first year after surgery, is associated with better visual acuity outcomes in children treated for unilateral congenital cataracts. Specifically, patching every day, either first thing in the morning and/or around the same time each day, as reported two months after surgery and at 13 months of age, is associated with an approximately two-fold increase in the likelihood that a child will attain near normal vision in the treated eye. Additionally, the average visual acuity among children whose caregivers report consistent patching in the first year after surgery is substantially better than if patching is performed less regularly.

We hypothesize that consistency in early patching supports the development of a patching routine that increases the likelihood of a good visual acuity outcome by making it easier for children to be patched throughout the amblyogenic period, by predicting future patching behaviors and by increasing the overall amount of time that children are patched.¹⁸ This hypothesis is supported in our data by the observation that caregivers who report consistent patching behaviors also report that their children are patched a greater number of hours per day, both during infancy and in the subsequent three years.

Consistency in patching in infancy, by patching every day around the same time, likely supports development of patching habits. Further, in one series, one-quarter of parents of children who were prescribed patching for amblyopia reported that patching was easier when their child was less than two years old; children 2 to 4 years of age were the most upset by patching,³⁸ suggesting that it may be easier to establish these patching habits in infancy. Similarly, earlier research reported higher rates of adherence in infancy and lower rates in toddlers.³⁹ Thus, infancy may represent a unique opportunity to establish patching routines in children treated for unilateral cataract.

Early patching is also likely to be associated with early improvements in visual acuity, which likely helps to minimize the child’s later resistance to patching. This is particularly important in toddlers who may protest against efforts to patch and/or remove the patch before they have the communication and cognitive ability to understand the importance of patching. Further, a number of studies have suggested that it is beneficial to provide programs to support patching soon after it is prescribed.³⁹ However, the immediate benefits of patching on visual acuity in infancy are difficult to measure because of the challenges of assessing visual acuity before measures of recognition visual acuity can be obtained. Therefore, providing caregivers tangible evidence regarding the efficacy of patching in infancy is particularly important for this patient group. Providing caregivers with information about the efficacy of patching has been shown to improve adherence to occlusion therapy in children with other types of amblyopia.^14,22,28,40 Thus, our results can be used by health care providers to develop simple educational messages that will help inform caregivers about the value of patching, and support their efforts to patch infants who are treated for unilateral congenital cataract.^25,26 Specifically, we provide data that can help caregivers understand the importance of maintaining a consistent patching schedule. Further, the health messages that we propose are relatively simple: patch half of every day starting either first thing in the morning or at the same time each day. Advising parents to anchor applying the patch to a daily activity, such as dressing, may also support patching consistency. Our results also highlight the importance of early patching behaviors, and prompt implementation of occlusion therapy, which may mitigate caregivers’ temptation to delay treatment.²⁶

Limitations:

These results come from a well-designed randomized controlled trial where patching was assessed prospectively over two 7-day time periods within the first year following cataract extraction. While we believe that our results support the message that establishing early patching habits supports development of good visual acuity in children treated for unilateral cataract, there are a few limitations to our findings. First, even in this early period, the child’s visual acuity may predict the amount and consistency of patching that a parent can provide. A randomized controlled trial comparing our proposed advice to patch around the same time every day to not providing advice on the timing of patching, would solidify our recommendations. Additionally, the overall sample size for some analyses is relatively small. For example, only 15 children were not patched every day two months after surgery. Therefore, some of our estimates are imprecise, the confidence intervals are wide and some of the associations do not achieve statistical significance. However, we believe our findings suggest a true association between patching habits and visual outcomes given the consistency of the direction of the associations. Further, these diaries cover only fourteen days of the first year following surgery. Therefore, the patching reported on these two diaries may differ from patching during other periods. We also note that the associations using data from the diary completed two months after surgery were not as robust as those using data collected on both diaries combined or at 13-months of age. We suspect that this is likely due to the fact that nearly two-thirds (61%) of these children were under 5-months of age at the time the first diary was completed. Establishing a routine for patching during this period may be particularly difficult since these infants may not yet have established a regular sleep and feeding routine. Similarly, the parents who agree to participate in randomized controlled trials may also differ from those parents seen in routine practice. Therefore, findings in a general clinical population may differ from those reported here.

We recognize that our results would likely be more robust had we used occlusion dose monitors to measure the timing of patching.⁴¹ We believe that our use of prospective patching diaries mitigates some of the concerns reflected in using caregiver-reported information. For example, rather than asking caregivers how many hours of patching were achieved, we asked caregivers to record each time the patch was applied and removed. Even so, we cannot be sure that caregivers completed the diaries prospectively or that the times were accurately recorded. We do not believe, however, that errors resulting from use of a diary, as compared to being objectively measured, would invalidate our observed associations since the reporting errors would likely be non-differentially distributed with respect to future visual acuity, and therefore our estimates are likely conservative.

Finally, we have assumed that our results come from a closed cohort. Thus, the risks of good visual acuity that we present may be somewhat biased by losses to follow-up and/or missing data. However, we believe that this is a minor concern since our cohort was defined by completion of one or more prospective patching diaries and only two of the more than 100 children in the cohort did not have data on visual acuity obtained at age 54 months. Five children from the cohort did not have visual acuity data at 10.5 years.

Summary:

In summary, we provide the first evidence-based results showing the relationship between patching behaviors reported by caregivers of children born with a unilateral cataract in the first year following cataract extraction and visual acuity later in childhood. Specifically, our findings provide information that consistency in the time of day when occlusion therapy is provided is associated with a greater chance that a child will achieve near normal visual acuity in the affected eye. This information can be used by healthcare providers to motivate caregivers to develop consistent patching habits. Further, providers can present caregivers with simple advice: apply the patch every day either first thing in the morning or about the same time every day.