Epidemiology & Technology

Stata Code for generating corneal opacity outcomes from RAAB 6 surveys

Generating PVA Better eye variable
tab1 status
gen enrol = status==1
egen pvaBetter = rowmin(pvare pvale) if enrol==1
Codes for vision
	   1   Can see 6/12
           2   Can see 6/18, Cannot see 6/12
           3   Can see 6/60, Cannot see 6/18
           4   Can see 3/60, Cannot see 6/60
           5   Can see 1/60, Cannot see 3/60
           6   PL+, Cannot see 1/60
           7   PL-
           9   Missing	    
Codes for Cause of vision loss: causep, causere, causele
           1   Refractive error
           2   Aphakia, uncorrected
           3   Cataract, untreated
           4   Cataract surg. complications
           5   Trachoma corneal opacity
           6   Other corneal opacity
           7   Phthisis
           8   Others/Undetermined
           9   Glaucoma
          10   Diabetic retinopathy
          11   ARMD
          12   Other posterior segment
          13   All globe/CNS abnormalities
          14   Not examined: can see 6/12
          99   Missing
    

Corneal Opacity Related Outcomes

There are four sets of variables

  1. First we identify persons who have better eye vision worse than the threshold, and have one or both eye marked as corneal opacity (unilateral / bilateral )
  2. Next we identify persons who have better eye vision worse than the threshold, and where cornal opacity is the most preventable cause of visual impairment
  3. Thirdly, we identify persons who have better eye vision worse than the threshold, and where cornal opacity is the most preventable cause of visual impairment and have at least percepton of light positive in one corneal opacity afected eye
  4. Finally, we identify persons who have better eye vision equal to or better than the threshhold, but have one eye affected with Corneal oapcity and in that eye, the vision is worse than the threshold

Stata Code

 
****************************************************************************************
** EVI, MSVI or blindness with    U/L, B/L or any Eye COs

*** The next set of variables identify 
*** those persons in whom CO is marked as the cause of PVA < 6/12 in one, two or any eye  
****** among persons who are at a specified threshold of PVA in better eye 

** This set of variables ignore cause of VI in the fellow eye
** Also, the PVA in CO afflicted eye is not taken into account. Only PVA better eye in person is taken into account

/*
EVI, MSVI or blindness with
Bilateral CO 	PVA < 6/12 in better eye, AND both eyes have corneal opacity noted as cause of PVA < 6/12	coVi612Bl
Unilateral CO	PVA < 6/12 in better eye, AND only one eye has corneal opacity noted as cause of PVA < 6/12	coVi612Ul

*/
cap drop coVi612
gen     coVi612 = 0
replace coVi612 = 2 if ///
		inlist(pvaBetter,2,3,4,5,6,7) &  ///
		(inlist(causere,5,6)  &  inlist(causele,5,6) ) & ///
		coVi612==0 
replace coVi612 = 1 if ///
		inlist(pvaBetter,2,3,4,5,6,7) & ///
		(inlist(causere,5,6)  |  inlist(causele,5,6) ) & ///
		coVi612==0
label var coVi612 "CO marked as cause in persons with PVA<6/12 Better Eye" 
label define coVi612 0 "No CO" 1 "U/L CO" 2 "B/L CO", replace
label value coVi612 coVi612
tab coVi612  
bysort coVi612: tab2   causere causele, nol
bysort coVi612: tab   prcause, nol

gen coVi612Ul       = coVi612==1
gen coVi612Bl      = coVi612==2
gen coVi612AnyEye = coVi612==1 | coVi612==2

label var  coVi612Ul      "Ul-CO marked as cause of PVA < 6/12 in persons with PVA < 6/12"
label var  coVi612Bl      "Bl-CO marked as cause of PVA < 6/12 in persons with PVA < 6/12"
label var  coVi612AnyEye  "Any eye CO marked as cause of PVA < 6/12 in persons with PVA < 6/12"
label define  coVi612Ul        0    "Not CO as cause of VI in one eye" 1 "Ul-CO marked as cause of PVA < 6/12 in persons with PVA < 6/12"
label value   coVi612Ul     coVi612Ul
label define  coVi612Bl       0  "Not CO as cause of VI in one eye" 1     "Bl-CO marked as cause of PVA < 6/12 in persons with PVA < 6/12"
label value   coVi612Bl     coVi612Bl
label define  coVi612AnyEye     0  "Not CO as cause of VI in any eye"  1  "Any eye CO marked as cause of PVA < 6/12 in persons with PVA < 6/12"
label value   coVi612AnyEye coVi612AnyEye



/*    A2. 
MSVI or Blindness with	
Bilateral CO 	PVA < 6/18 in better eye, AND Both eyes have corneal opacity noted as cause of PVA < 6/12	coVi618Bl	  
Unilateral CO	PVA < 6/18 in better eye, AND only one eye has corneal opacity noted as cause of PVA < 6/12	coVi618Ul  
*/
cap drop coVi618
gen     coVi618 = 0
replace coVi618 = 2 if ///
		inlist(pvaBetter,3,4,5,6,7) &  ///
		(inlist(causere,5,6)  &  inlist(causele,5,6) ) & ///
		coVi618==0 
replace coVi618 = 1 if ///
		inlist(pvaBetter,3,4,5,6,7) & ///
		(inlist(causere,5,6)  |  inlist(causele,5,6) ) & ///
		coVi618==0
label var coVi618  "CO marked as cause in persons with PVA<6/18 Better Eye"  
label define coVi618 0 "No CO" 1 "U/L CO" 2 "B/L CO", replace
label value coVi618 coVi618
tab coVi618  
bysort coVi618: tab2   causere causele, nol
bysort coVi618: tab   prcause, nol

gen coVi618Ul       = coVi618==1
gen coVi618Bl      = coVi618==2
gen coVi618AnyEye = coVi618==1 | coVi618==2

label var     coVi618Ul     "Ul-CO marked as cause of PVA < 6/12 in persons with PVA < 6/18"
label var     coVi618Bl     "Bl-CO marked as cause of PVA < 6/12 in persons with PVA < 6/18"
label var     coVi618AnyEye  "Any eye CO marked as cause of PVA < 6/12 in persons with PVA < 6/18"
label define  coVi618Ul        0    "Not CO as cause of MSVIB in one eye" 1  "Ul-CO marked as cause of PVA < 6/12 in persons with PVA < 6/18"
label value   coVi618Ul     coVi618Ul
label define  coVi618Bl       0  "Not CO as cause of MSVIB in one eye" 1     "Bl-CO marked as cause of PVA < 6/12 in persons with PVA < 6/18"
label value   coVi618Bl     coVi618Bl
label define  coVi618AnyEye     0  "Not CO as cause of MSVIB in any eye"  1  "Any eye CO marked as cause of PVA < 6/12 in persons with PVA < 6/18"
label value   coVi618AnyEye coVi618AnyEye


/* A3.
SVI or Blindness with	
Bilateral CO 	PVA < 6/60 in better eye, AND Both eyes have corneal opacity noted as cause of PVA < 6/12	coVi660Bl 
Unilateral CO	PVA < 6/60 in better eye, And only one eye has corneal opacity noted as cause of PVA < 6/12	coVi660Ul	 
 */
cap drop coVi660
gen     coVi660 = 0
replace coVi660 = 2 if ///
		inlist(pvaBetter,4,5,6,7) &  /// PVA , 6/60
		(inlist(causere,5,6)  &  inlist(causele,5,6) ) & ///
		coVi660==0 
replace coVi660 = 1 if ///
		inlist(pvaBetter,4,5,6,7) & ///
		(inlist(causere,5,6)  |  inlist(causele,5,6) ) & ///
		coVi660==0
label var coVi660 "CO marked as cause in persons with PVA<6/60 Better Eye" 
label define coVi660 0 "No CO" 1 "U/L CO" 2 "B/L CO", replace
label value coVi660 coVi660
tab coVi660  
bysort coVi660: tab2   causere causele, nol
bysort coVi660: tab   prcause, nol

gen coVi660Ul       = coVi660==1
gen coVi660Bl       = coVi660==2
gen coVi660AnyEye   = coVi660==1 | coVi660==2

label var  coVi660Ul      "Ul-CO marked as cause of PVA < 6/12 in persons with PVA < 6/60"
label var  coVi660Bl      "Bl-CO marked as cause of PVA < 6/12 in persons with PVA < 6/60"
label var  coVi660AnyEye  "Any eye CO marked as cause of PVA < 6/12 in persons with PVA < 6/60"
label define  coVi660Ul        0    "Not CO as cause of SVIB in one eye" 1 "Ul-CO marked as cause of PVA < 6/12 in persons with PVA < 6/60"
label value   coVi660Ul     coVi660Ul
label define  coVi660Bl       0  "Not CO as cause of SVIB in one eye" 1     "Bl-CO marked as cause of PVA < 6/12 in persons with PVA < 6/60"
label value   coVi660Bl     coVi660Bl
label define  coVi660AnyEye     0  "Not CO as cause of SVIB in any eye"  1  "Any eye CO marked as cause of PVA < 6/12 in persons with PVA < 6/60"
label value   coVi660AnyEye coVi660AnyEye


/* A4. Blindness with	
Bilateral CO 	PVA < 3/60 in better eye,
 AND Both eyes have corneal opacity noted as cause of PVA < 6/12	coVi360Bl	 
Unilateral CO	PVA < 3/60 in better eye, 
AND only one eye has corneal opacity noted as cause of PVA < 6/12	coVi360Ul	  
 */
cap drop coVi360
gen     coVi360 = 0
replace coVi360 = 2 if ///
		inlist(pvaBetter,5,6,7) &  ///
		(inlist(causere,5,6)  &  inlist(causele,5,6) ) & ///
		coVi360==0 
replace coVi360 = 1 if ///
		inlist(pvaBetter,5,6,7) & ///
		(inlist(causere,5,6)  |  inlist(causele,5,6) ) & ///
		coVi360==0
label var coVi360 "CO as cause of PVA<3/60 in eyes" 
label define coVi360 0 "No CO" 1 "U/L CO" 2 "B/L CO", replace
label value coVi360 coVi360
tab coVi360  
bysort coVi360: tab2   causere causele, nol
bysort coVi360: tab   prcause, nol

gen coVi360Ul       = coVi360==1
gen coVi360Bl      = coVi360==2
gen coVi360AnyEye = coVi360==1 | coVi360==2

label var  coVi360Ul      "Ul-CO marked as cause of PVA < 6/12 in persons with PVA < 3/60"
label var  coVi360Bl      "Bl-CO marked as cause of PVA < 6/12 in persons with PVA < 3/60"
label var  coVi360AnyEye  "Any eye CO marked as cause of PVA < 6/12 in persons with PVA < 3/60"
label define  coVi360Ul        0    "Not CO as cause of Blindness in one eye" 1 "Ul-CO marked as cause of PVA < 6/12 in persons with PVA < 3/60"
label value   coVi360Ul     coVi360Ul
label define  coVi360Bl       0  "Not CO as cause of Blindness in one eye" 1     "Bl-CO marked as cause of PVA < 6/12 in persons with PVA < 3/60"
label value   coVi360Bl     coVi360Bl
label define  coVi360AnyEye     0  "Not CO as cause of Blindness in any eye"  1  "Any eye CO marked as cause of PVA < 6/12 in persons with PVA < 3/60"
label value   coVi360AnyEye coVi360AnyEye



************************************************************************
* Persons with PREVENTABLE BLINDNESS OR VI DUE TO COs
*** It may happen that persons with one eye CO may have a more preventable / treatable cause in other eye
*** The next set of variables identify those persons in whom CO is marked as cause at specified PVA threhold in that eye, 
*** and the fellow eye has a less avoidable /treatable cause
******* among persons who are at a specified threshold of PVA in better eye 

** This set of variables DO NOT ignore  cause of VI in  the fellow eye
** Also, the PVA in CO afflicted eye IS taken into account. 
** Thereby these overcome some of the limitations of previous set of variables

****************************************************************************

/*
B1. Avoidable EVI, MSVI or blindness due to CO potentially amenable to keratoplasty	PVA < 6/12 in better eye, 
AND either 
a.	Only one eye has corneal opacity noted as cause of visual impairment and has PVA < 3/60, with fellow eye having a less avoidable cause of visual impairment, OR
b.	Both eyes have corneal opacity noted as cause of visual impairment and have PVA < 3/60
AND at least one CO affected eye has perception of light
– RAAB protocol ensures that these have PVA worse than 6/12 in better eye
*/ 

cap drop coVi612prev
gen coVi612prev = 0
replace coVi612prev = 1 if inlist(pvaBetter,2,3,4,5,6,7) & (inlist(prcause,5,6))  & coVi612prev==0 
tab coVi612prev //  275
tab coVi612prev coVi612
label var  coVi612prev 		    "CO main cause of PVA < 6/12 in person" 
label define  coVi612prev   0    "Not Preventable VIB  due to CO" 1 "CO main cause of PVA < 6/12 in person"
label value   coVi612prev     coVi612prev

/* B2. Avoidable MSVI or blindness due to CO	
PVA < 6/18 in better eye,
 AND either 
a.	Only one eye has corneal opacity noted as cause of visual impairment and has PVA < 6/18, with fellow eye having a less avoidable cause of visual impairment, OR
b.	Both eyes have corneal opacity noted as cause of visual impairment and have PVA < 6/18
*/
cap drop coVi618prev
gen coVi618prev = 0
replace coVi618prev = 1 if ///
	inlist(pvaBetter,3,4,5,6,7) & /// Person has MSVI or blindness, AND
	 ( /// One of the following three conditions are met
	   (  inlist(causere, 5,6) & inlist(pvare, 3,4,5,6,7) & inlist(causele,7,8,9,10,11,12,13)  )   |  /// 1. Right eye has CO (5,6) and Rt pva < 6/18 and Left eye has less avoidable cause of PVA < 6/12 (7-13) OR 
	   (  inlist(causele, 5,6) & inlist(pvale, 3,4,5,6,7) & inlist(causere,7,8,9,10,11,12,13)  )   |  /// 2. Left eye has CO (5,6) and Lt pva < 6/18 and Right eye has less avoidable cause of PVA < 6/12  (7-13) OR 
	   (  inlist(causere, 5,6) & inlist(pvare, 3,4,5,6,7) & inlist(causele, 5,6) & inlist(pvale, 3,4,5,6,7)   )		/// 3. BOTH Right eye has CO pva < 6/18,  Left eye has CO (5,6) pva < 6/18   
	  )
tab coVi618prev
tab coVi618prev coVi618
label var  coVi618prev  "CO main cause of PVA < 6/18 in person"
label define  coVi618prev        0    "Not Preventable MSVIB due to CO" 1 "CO main cause of PVA < 6/18 in person"
label value   coVi618prev     coVi618prev


/* B3. Avoidable SVI or blindness due to CO	
PVA < 6/60 in better eye,
 AND either 
a.	Only one eye has corneal opacity noted as cause of visual impairment and has PVA < 6/60, with fellow eye having a less avoidable cause of visual impairment, OR
b.	Both eyes have corneal opacity noted as cause of visual impairment and have PVA < 6/60
 */
cap drop coVi660prev
gen coVi660prev = 0
replace coVi660prev = 1  if ///
	inlist(pvaBetter,4,5,6,7) & ///
	 ( ///
	   (  inlist(causere, 5,6) & inlist(pvare, 4,5,6,7) & inlist(causele,7,8,9,10,11,12,13)  )   |  /// Right eye has CO (5,6) and rt pva < 6/60  and Left eye has (7-13) OR 
	   (  inlist(causele, 5,6) & inlist(pvale, 4,5,6,7) & inlist(causere,7,8,9,10,11,12,13)  )   |  /// Left eye has CO (5,6) and Lt pva < 6/60   , Right eye has (7-13) OR 
	   (  inlist(causere, 5,6) & inlist(pvare, 4,5,6,7) & inlist(causele, 5,6) & inlist(pvale, 4,5,6,7)   )		/// Right eye has CO (5,6) pva < 6/60  ,  Left eye has CO (5,6) pva < 6/60 
	  )
tab coVi660prev //  275
tab coVi660prev coVi660
label var  coVi660prev "CO main cause of PVA < 6/60 in person" 
label define  coVi660prev        0    "Not Preventable SVIB due to CO" 1 "CO main cause of PVA < 6/60 in person"
label value   coVi660prev     coVi660prev

/* B4. Avoidable Blindness due to CO	
PVA < 3/60 in better eye, 
AND either 
a.	Only one eye has corneal opacity noted as cause of visual impairment and has PVA < 3/60, with fellow eye having a less avoidable cause of visual impairment, OR
b.	Both eyes have corneal opacity noted as cause of visual impairment and have PVA < 3/60   */
cap drop coVi360prev
gen coVi360prev = 0
replace coVi360prev = 1 if ///
	inlist(pvaBetter,5,6,7) & ///
	 ( ///
	   (  inlist(causere, 5,6) & inlist(pvare, 5,6,7) & inlist(causele,7,8,9,10,11,12,13)  )   |  /// Right eye has CO (5,6) and rt pva < 3/60  and Left eye has (7-13) OR 
	   (  inlist(causele, 5,6) & inlist(pvale, 5,6,7) & inlist(causere,7,8,9,10,11,12,13)  )   |  /// Left eye has CO (5,6) and Lt pva < 3/60  , Right eye has (7-13) OR 
	   (  inlist(causere, 5,6) & inlist(pvare, 5,6,7) & inlist(causele, 5,6) & inlist(pvale, 5,6,7)   )		/// Right eye has CO (5,6) pva < 3/60 ,  Left eye has CO (5,6) pva < 3/60  
	  )
	  
tab coVi360prev //  177
label var  coVi360prev "CO main cause of PVA < 3/60 in person" 
label define  coVi360prev        0    "Not Preventable Blindness due to CO" 1 "CO main cause of PVA < 3/60 in person"
label value   coVi360prev     coVi360prev



************************************************************************
* Persons with Surgically TREATABLE BLINDNESS OR VI DUE TO COs - 
*** It may happen that persons with CO may have PL-ve vision and therefore are non-treatable by keratoplasty services. 

*** The next set of variables identify those persons in whom CO is marked at the more preventable cause at specified PVA threhold in that eye, 
*** and the CO affected eye has PL+ve vision
*** and the fellow eye has a less avoidable /treatable cause and may be PL-ve
******* among persons who are at a specified threshold of PVA in better eye 

** This set of variables DO NOT ignore  cause of VI in  the fellow eye
** Also, the PVA in CO afflicted eye and PL+ positivity IS taken into account. 
** Thereby these overcome some of the limitations of previous set of variables

****************************************************************************
	
/*
C1. 
Avoidable EVI, MSVI or blindness due to CO potentially amenable to keratoplasty	
PVA < 6/12 in better eye, 
AND either 
a.	Only one eye has corneal opacity noted as cause of visual impairment and has PVA < 3/60, with fellow eye having a less avoidable cause of visual impairment, OR
b.	Both eyes have corneal opacity noted as cause of visual impairment and have PVA < 3/60
AND at least one CO affected eye has perception of light

PVA < 6/12 IN BETTER EYE AND 
-	Right eye has CO and is PL+ and left eye is 7-13
-	Left eye has CO and is PL+ and Right eye is 7-13
-	Both eyes have CO and one eye is PL+
*/
cap drop coVi612prevSurg
gen coVi612prevSurg = 0
replace coVi612prevSurg = 1 if ///
	inlist(pvaBetter,2,3,4,5,6,7) & ///
	 ( ///
	   (  inlist(causere, 5,6) & inlist(pvare, 2,3,4,5,6) & inlist(causele,7,8,9,10,11,12,13) & inlist(pvale, 2, 3,4,5,6,7)  )   |  /// Right eye has CO and is PL+ and left eye is 7-13
	   (  inlist(causele, 5,6) & inlist(pvale, 2,3,4,5,6) & inlist(causere,7,8,9,10,11,12,13)  & inlist(pvare, 2, 3,4,5,6,7) )   |  /// Left eye has CO and is PL+ and Right eye is 7-13
	   (  inlist(causere, 5,6) & inlist(causele, 5,6)  & inlist(pvare, 2,3,4,5,6,7)  & inlist(pvale, 2,3,4,5,6,7) &  (inlist(pvale,1,2,3,4,5,6) | inlist(pvare,1,2,3,4,5,6))   )	/// Both eyes have CO and both eye cannot see PVA  6/12 and one eye is PL+  
	  )
tab coVi612prevSurg

/* C2. Avoidable MSVI or blindness due to CO Potentially amenable to keratoplasty	
PVA < 6/18 in better eye,
 AND either 
a.	Only one eye has corneal opacity noted as cause of visual impairment and has PVA < 3/60, with fellow eye having a less avoidable cause of visual impairment, OR
b.	Both eyes have corneal opacity noted as cause of visual impairment and have PVA < 3/60
AND at least one CO affected eye has perception of light
*/
cap drop coVi618prevSurg
gen coVi618prevSurg = 0
replace coVi618prevSurg = 1 if ///
	inlist(pvaBetter,3,4,5,6,7) & ///
	 ( ///
	   (  inlist(causere, 5,6) & inlist(pvare, 3,4,5,6) & inlist(causele,7,8,9,10,11,12,13)  & inlist(pvale, 3,4,5,6,7)  )   |  /// Right eye has CO and cannot see PVA  6/18 and is PL+; left eye is 7-13 and cannot see PVA  6/18
	   (  inlist(causele, 5,6) & inlist(pvale, 3,4,5,6) & inlist(causere,7,8,9,10,11,12,13)  & inlist(pvare, 3,4,5,6,7)  )   |  /// Left eye has CO and is PL+ and cannot see PVA 6/18 and; Right eye is 7-13 and cannot see PVA  6/18
	   (  inlist(causere, 5,6) & inlist(causele, 5,6) & inlist(pvare, 3,4,5,6,7)  & inlist(pvale, 3,4,5,6,7) &    (inlist(pvale,1,2,3,4,5,6) | inlist(pvare,1,2,3,4,5,6))    )	/// Both eyes have CO and both eye cannot see PVA  6/18 and one eye is PL+
	 )  
tab coVi618prevSurg	
	
/* C3. Avoidable SVI or blindness due to CO Potentially amenable to keratoplasty	
PVA < 6/60 in better eye, 
AND either 
a.	Only one eye has corneal opacity noted as cause of visual impairment and has PVA < 3/60, with fellow eye having a less avoidable cause of visual impairment, OR
b.	Both eyes have corneal opacity noted as cause of visual impairment and have PVA < 3/60
AND at least one CO affected eye has perception of light

*/
cap drop coVi660prevSurg
gen coVi660prevSurg = 0
replace coVi660prevSurg = 1 if ///
	inlist(pvaBetter,4,5,6,7) & ///
	 ( ///
	   (  inlist(causere, 5,6) & inlist(pvare, 4,5,6) & inlist(causele,7,8,9,10,11,12,13)  & inlist(pvale, 4,5,6,7)  )   |  /// Right eye has CO and cannot see PVA  6/60 and is PL+; left eye is 7-13 and cannot see PVA  6/60
	   (  inlist(causele, 5,6) & inlist(pvale, 4,5,6) & inlist(causere,7,8,9,10,11,12,13)  & inlist(pvare, 4,5,6,7)  )   |  /// Left eye has CO and is PL+ and cannot see PVA 6/60 and; Right eye is 7-13 and cannot see PVA  6/60
	   (  inlist(causere, 5,6) & inlist(causele, 5,6) & inlist(pvare, 4,5,6,7)  & inlist(pvale, 4,5,6,7) &   (inlist(pvale,1,2,3,4,5,6) | inlist(pvare,1,2,3,4,5,6))   )	/// Both eyes have CO and both eye cannot see PVA  6/60 and one eye is PL+
	  )
tab coVi660prevSurg		

				
/* C4.Avoidable Blindness due to CO Potentially amenable to keratoplasty
PVA < 3/60 in better eye, 
AND either 
a.	Only one eye has corneal opacity noted as cause of visual impairment and has PVA < 3/60, with fellow eye having a less avoidable cause of visual impairment, OR
b.	Both eyes have corneal opacity noted as cause of visual impairment and have PVA < 3/60
AND at least one CO affected eye has perception of light
*/		
cap drop coVi360prevSurg
gen coVi360prevSurg = 0
replace coVi360prevSurg = 1 if ///
	inlist(pvaBetter,5,6,7) & ///
	(  ///
	   (  inlist(causere, 5,6) & inlist(pvare, 5,6) & inlist(causele,7,8,9,10,11,12,13)  & inlist(pvale, 5,6,7)  )   |  /// Right eye has CO and cannot see PVA  3/60 and is PL+; left eye is 7-13 and cannot see PVA  3/60
	   (  inlist(causele, 5,6) & inlist(pvale, 5,6) & inlist(causere,7,8,9,10,11,12,13)  & inlist(pvare, 5,6,7)  )   |  /// Left eye has CO and is PL+ and cannot see PVA 3/60 and; Right eye is 7-13 and cannot see PVA  3/60
	   (  inlist(causere, 5,6) & inlist(causele, 5,6) & inlist(pvare, 5,6,7)  & inlist(pvale, 5,6,7) &   (inlist(pvale,1,2,3,4,5,6) | inlist(pvare,1,2,3,4,5,6))  )	/// Both eyes have CO and both eye cannot see PVA  3/60 and one eye is PL+
	 )
tab coVi360prevSurg		

label var  		coVi612prevSurg "Surgically amenable VI or blindness  due to CO" 
label define  coVi612prevSurg        0    "Not Surgically amenable VIB  due to CO" 1 "Surgically amenable VI or blindness  due to CO"
label value   coVi612prevSurg     coVi612prevSurg
	
label var  coVi618prevSurg "Surgically amenable MSVI or blindness  due to CO" 		
label define  coVi618prevSurg        0    "Not Surgically amenable MSVI due to CO" 1 "Surgically amenable MSVI or blindness due to CO"
label value   coVi618prevSurg     coVi618prevSurg

label var  coVi660prevSurg "Surgically amenable SVI or blindness due to CO" 					
			
label define  coVi660prevSurg        0    "Not Surgically amenable SVIB due to CO" 1 "Surgically amenable SVI or blindness due to CO"
label value   coVi660prevSurg     coVi660prevSurg

label var  coVi360prevSurg "Surgically amenable  blindness due to CO" 				
label define  coVi360prevSurg        0    "Not Surgically amenable blindness due to CO" 1 "Surgically amenable blindness due to CO"
label value   coVi360prevSurg     coVi360prevSurg
				

************************************************************************ 
** SO far, the starting point has been person having PVA < 6/12 and identifying how many had CO in one or both eyes
*** The next set of variables identify 
*** those persons in whom CO is marked as the cause of PVA < 6/12 in one, two eyes  
****** among persons who are ABOVE specified threshold of PVA in better eye 
** Therefore, now we identify persons with NO VI at person level but having one or both eye VI and CO in that eye

* D1. No EVI, MSVI or blindness, unilateral CO with PVA  6/12 in affected eye 
cap drop coNoVi612
gen     coNoVi612 = 0
// replace coNoVi612 = 2 if ///
// 		inlist(pvaBetter,1) &  /// PVA better eye - Can see  6/12
// 		(inlist(causere,5,6)  &  inlist(causele,5,6) ) & /// Both eyes have CAO as cause of PVA < 6/12 - will be ZERO always as cuase is not marked iv PVA is can see 6/12
// 		coNoVi612==0 
replace coNoVi612 = 1 if ///
		inlist(pvaBetter,1) & ///
		(inlist(causere,5,6)  |  inlist(causele,5,6) ) & /// Any One eye cause of PVA < 6/12 is CO 
		coNoVi612==0
label var coNoVi612 "CO in any eye but NO VI in person" 
label define coNoVi612 0 "PVA >= 6/12 without CO or EMSVIB with CO" 1 "U/L CO PVA < 6/12, no VI" 2 "B/L CO with no VI", replace
label value coNoVi612 coNoVi612
tab coNoVi612


* D2. No MSVI or blindness, unilateral CO with PVA < 6/18 in affected eye 
tab pvaBetter coVi618
cap drop coNoVi618
gen     coNoVi618 = 0
// replace coNoVi618 = 2 if ///    
// 		inlist(pvaBetter,1,2) &  /// PVA better eye - Can see 6/18
// 		(inlist(causere,5,6)  &  inlist(causele,5,6) & inlist(pvare, 3,4,5,6,7)   & inlist(pvale, 3,4,5,6,7)   ) & /// Both eyes have CO as cause of PVA < 6/18  - will be ZERO
// 		coNoVi618==0 
replace coNoVi618 = 1 if ///
		inlist(pvaBetter,1,2) & ///  PVA better eye - Can see 6/18
		(  ///
			( inlist(causere,5,6) & inlist(pvare, 3,4,5,6,7) ) |  /// Right eye has CO as cause of PVA <6/12 
			( inlist(causele,5,6) & inlist(pvale, 3,4,5,6,7) )    /// Left  eye has CO as cause of PVA <6/12 
		)    &  /// 
		coNoVi618==0 //
		
label var coNoVi618 "CO in any eye but NO MSVIB in person" 
label define coNoVi618 0 "PVA >= 6/18 without CO OR MSVIB with CO" 1 "U/L CO with no MSVIB" 2 "B/L CO with no MSVIB", replace
label value coNoVi618 coNoVi618
tab   pvaBetter coNoVi618
tab   pvaBetter coNoVi612


* D3. No SVI or blindness, unilateral CO with PVA < 6/60 in affected eye
tab pvaBetter coVi660
cap drop coNoVi660
gen     coNoVi660 = 0
// replace coNoVi660 = 2 if ///
// 		inlist(pvaBetter,1,2,3) &  /// PVA better eye - Can see 6/60
// 		(inlist(causere,5,6)  &  inlist(causele,5,6) & inlist(pvare, 4,5,6,7)   & inlist(pvale, 4,5,6,7)  ) & /// Both eye has CO as cause of PVA < 6/60 - will be ZERO
// 		coNoVi660==0 
replace coNoVi660 = 1 if ///
		inlist(pvaBetter,1,2,3) & /// PVA better eye - Can see 6/60
		(  ///
			( inlist(causere,5,6) & inlist(pvare, 4,5,6,7) ) |  /// Right eye has CO as cause of PVA <6/60  
			( inlist(causele,5,6) & inlist(pvale, 4,5,6,7) )    /// Left  eye has CO as cause of PVA <6/60
		)    &  /// 
		coNoVi660==0 //
		
label var coNoVi660 "CO in any eye but NO SVIB in person" 
label define coNoVi660 0 "PVA >= 6/60 without CO or SVIB with CO"  1 "U/L CO with no SVIB" 2 "B/L CO with no SVIB", replace
label value coNoVi660 coNoVi660



* D4. No blindness, unilateral CO with PVA < 3/60 in affected eye 
tab pvaBetter coVi360
cap drop coNoVi360
gen     coNoVi360 = 0
// replace coNoVi360 = 2 if ///
// 		inlist(pvaBetter,1,2,3,4) &  ///  PVA better eye - Can see 3/60
// 		(inlist(causere,5,6)  &  inlist(causele,5,6) & inlist(pvare, 5,6,7)   & inlist(pvale, 5,6,7)  ) & /// Both eye has CO as cause of PVA < 3/60 - will be ZERO
// 		coNoVi360==0 
replace coNoVi360 = 1 if ///
		inlist(pvaBetter,1,2,3,4) & /// PVA better eye - Can see  3/60
		(  ///
			( inlist(causere,5,6) & inlist(pvare, 5,6,7) ) |  /// Right eye has CO as cause of PVA <3/60 
			( inlist(causele,5,6) & inlist(pvale, 5,6,7) )    /// Left  eye has CO as cause of PVA <3/60 
		)    &  /// 
		coNoVi360==0 //
		
label var coNoVi360 "CO in any eye but NO Bl in person" 
label define coNoVi360 0 "PVA >= 3/60 without CO or Blindness with CO" 1 "U/L CO with no Bl" 2 "B/L CO with no Bl", replace
label value coNoVi360 coNoVi360

tab   pvaBetter coNoVi360
tab   pvaBetter coNoVi660
tab   pvaBetter coNoVi618
tab   pvaBetter coNoVi612


gsort coNoVi360
list pvare pvale  pvaBetter causere causele prcause  coNoVi360 if coNoVi360 > 0, noobs clean

gsort coNoVi660
list pvare pvale  pvaBetter causere causele prcause  coNoVi660 if coNoVi660 > 0, noobs clean

gsort coNoVi618
list pvare pvale  pvaBetter causere causele prcause  coNoVi618 if coNoVi618 > 0, noobs clean

gsort coNoVi612
list pvare pvale  pvaBetter causere causele prcause  coNoVi612 if coNoVi612 > 0, noobs clean



Code language: Stata (stata)

The above Stata code can be used by anyone under a CC-BY-SA license.

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