HISTORY OF GLAUCOMA CATARACTS & GLAUCOMAS WERE UNDIFFERENTIATED & BOTH TERMS WERE USED FOR BLINDNESS UNTIL IST CENTURY. CATARACTS & GLAUCOMAS WERE UNDIFFERENTIATED & BOTH TERMS WERE USED FOR BLINDNESS UNTIL IST CENTURY. LATER ON DIFFERENTIATED: CATARACTS WERE TREATABLE BUT GLAUCOMAS WERE NOT. LATER ON DIFFERENTIATED: CATARACTS WERE TREATABLE BUT GLAUCOMAS WERE NOT. IN GLAUCOMAS BLINDNESS WAS ASSOCIATED WITH SEA COLORED PUPLIL. IN GLAUCOMAS BLINDNESS WAS ASSOCIATED WITH SEA COLORED PUPLIL. IN 10 TH CENTURY GLAUCOMAS WERE FIRST DESCRIBED TO BE ASSOCIATED WITH HIGH TENSION & IFLAMMATION IN ARABIAN WRTITINGS BY AT-TABARI. IN 10 TH CENTURY GLAUCOMAS WERE FIRST DESCRIBED TO BE ASSOCIATED WITH HIGH TENSION & IFLAMMATION IN ARABIAN WRTITINGS BY AT-TABARI. 1850’s WAS GREAT EPOCH IN GLAUCOMA DUE TO INVENTION OF OPHTHALMOSCOPE. BLINDNESS WITH HIGH TENSION, CUPPED DISC BUT NO CONGESTION WERE CLASSIFIED AS SIMPLE GLAUCOMA AND WITH CONGESTION AS ACUTE & SECONDARY. 1850’s WAS GREAT EPOCH IN GLAUCOMA DUE TO INVENTION OF OPHTHALMOSCOPE. BLINDNESS WITH HIGH TENSION, CUPPED DISC BUT NO CONGESTION WERE CLASSIFIED AS SIMPLE GLAUCOMA AND WITH CONGESTION AS ACUTE & SECONDARY. Source: Duke Elder Source: Duke Elder

POSTERIOR SCLERA: MODEL POSTERIOR SCLERA: MODEL POSTERIOR SCLERA & SCLERAL OPENING WITHOUT RETINA, OPTIC DISC AND CHOROID. POSTERIOR SCLERA & SCLERAL OPENING WITHOUT RETINA, OPTIC DISC AND CHOROID.

Nerve Fiber Layers DIAGRAMATIC VIEW OF RETINAL NERVE FIBERS DIAGRAMATIC VIEW OF RETINAL NERVE FIBERS

Arrangement of nerve fibers in optic disc Black are macular Black are macular Yellow are nasal Yellow are nasal Blue are arcuate Blue are arcuate All fibers meet in the center All fibers meet in the center MODIFIED FROM WOLFF’ ANATOMY

NERVE FIBERS DISTRIBUTION ARCUATE (BLUE) FIBERS ARE THE FIRST TO BE DESTROYED IN GLAUCOMA GIVING RISE TO ARCUATE FIELD DEFECTS

THERE IS NO PATHOLOGY WHICH CAN SELECTIVELY DESTROY ARCUATE FIBERS EITHER IN THE RETINA OR IN THE OPTIC DISC IN A SHARPLY DEFINED WAY !

Single & Double Arcuate Field Defects Superior arcuate field defect due to loss of inferior arcuate fibers. Superior arcuate field defect due to loss of inferior arcuate fibers. Double arcuate field defects are due to loss of both superior & inferior arcuate fibers. Double arcuate field defects are due to loss of both superior & inferior arcuate fibers. Taken from Duke-Elder, S: System of Ophthalmology

COULD THE OPTIC DISC BE THE PRIMARY SITE OF INJURY IN GLAUCOMA? NOT LIKELY DUE TO FOLLOWING REASON. NOT LIKELY DUE TO FOLLOWING REASON. HIGH IOP, OPTIC NEUROPATHY OR ANY OTHER PATHOLOGY CAN’T SELECTIVELY DESTROY ONLY THE ARCUATE FIBERS OUT OF ONE MILLION DENSELY PACKED N. FIBERS IN THE OPTIC DISC IN THE EARLY STAGES OF GLAUCOMA. HIGH IOP, OPTIC NEUROPATHY OR ANY OTHER PATHOLOGY CAN’T SELECTIVELY DESTROY ONLY THE ARCUATE FIBERS OUT OF ONE MILLION DENSELY PACKED N. FIBERS IN THE OPTIC DISC IN THE EARLY STAGES OF GLAUCOMA.

COULD THE RETINA BE THE PRIMARY SITE OF INJURY IN GLAUCOMA? NOT LIKELY DUE TO FOLLOWING REASONS. NOT LIKELY DUE TO FOLLOWING REASONS. HIGH IOP OR IN FACT ANY PATHOLOGY CAN’T SELECTIVELY DESTROY ONLY THE ARCUATE FIBERS OR THE GANGLION CELLS SERVING THE ARCUATE FIBERS OUT OF ONE MILLION N. FIBERS SPREAD OUT IN THE RETINA IN EARLY STAGES OF GLAUCOMA. HIGH IOP OR IN FACT ANY PATHOLOGY CAN’T SELECTIVELY DESTROY ONLY THE ARCUATE FIBERS OR THE GANGLION CELLS SERVING THE ARCUATE FIBERS OUT OF ONE MILLION N. FIBERS SPREAD OUT IN THE RETINA IN EARLY STAGES OF GLAUCOMA.

Could the scleral edge be the primary site of injury in glaucoma? Very likely, on the basis of arcuate field defects. In the temporal part the peripheral fibers have to arch above and below the macular fibers in order to reach the disc. As the temporal part of the disc sinks the entire temporal fibers are stretched and cut at the scleral edge. Arcuate fibers being scant deplete earlier giving rise to double arcuate field defect whereas the macular fiber being plentiful last till the end. Very likely, on the basis of arcuate field defects. In the temporal part the peripheral fibers have to arch above and below the macular fibers in order to reach the disc. As the temporal part of the disc sinks the entire temporal fibers are stretched and cut at the scleral edge. Arcuate fibers being scant deplete earlier giving rise to double arcuate field defect whereas the macular fiber being plentiful last till the end.

HISTORY OF TERM ‘CUPPING’ INTRODUCTION OF OPHTHALMOSCOPE IN 1851 BY Von Hemholtz. INTRODUCTION OF OPHTHALMOSCOPE IN 1851 BY Von Hemholtz. Jacobson, Jaeger, Graefe, Heinrich Muller(1856) & others CLASSIFIED SIMPLE GLAUCOMA IN WHICH EYEBALLS WERE FIRM BUT NON- CONGESTED. Jacobson, Jaeger, Graefe, Heinrich Muller(1856) & others CLASSIFIED SIMPLE GLAUCOMA IN WHICH EYEBALLS WERE FIRM BUT NON- CONGESTED. OPTIC DISCS WERE FOUND EXCAVATED AND WERE DESCRIBED AS ‘CUPPING’. OPTIC DISCS WERE FOUND EXCAVATED AND WERE DESCRIBED AS ‘CUPPING’. SINCE THEN THE TERM ‘CUPPING’ BECAME SYNONYMOUS WITH GLAUCOMA. SINCE THEN THE TERM ‘CUPPING’ BECAME SYNONYMOUS WITH GLAUCOMA.

POINTS AGAINST ‘CUPPING’ Cupping which implies that pathology starts concentrically can’t selectively destroy the arcuate fibers & not touch the remaining. Cupping which implies that pathology starts concentrically can’t selectively destroy the arcuate fibers & not touch the remaining. IF cupping started from the center then central vision would be lost first which is not the case. IF cupping started from the center then central vision would be lost first which is not the case. High IOP would more likely push the disc out of scleral opening rather concentric enlargement of original cup. High IOP would more likely push the disc out of scleral opening rather concentric enlargement of original cup. Kinking of vessels at margin while no change in original cup suggest sinking and not cupping. Kinking of vessels at margin while no change in original cup suggest sinking and not cupping.

POINTS IN FAVOR OF SINKING Sinking of disc implies herniating through scleral canal in its entirety. Sinking of disc implies herniating through scleral canal in its entirety. As the optic disc sinks the nerve fibers are compressed, stretched and cut at the scleral edge starting from peripheral deeper to central superficial fibers. As the optic disc sinks the nerve fibers are compressed, stretched and cut at the scleral edge starting from peripheral deeper to central superficial fibers. In the temporal part the peripheral arcuate fibers being scant would be depleted first. In the temporal part the peripheral arcuate fibers being scant would be depleted first. Sinking would explain the early arcuate field defect. Sinking would explain the early arcuate field defect. In sinking the central fibers would be last to be destroyed at the scleral edge explaining retention of central vision till the end. In sinking the central fibers would be last to be destroyed at the scleral edge explaining retention of central vision till the end.

WHY THE OPTIC DISC WOULD SINK? OPTIC DISC IS FASTENED IN SCLERAL OPENING BY CIRCULAR BORDER TISSUE & ANCHORAGE BY N.FIBERS AS ROOTS DO TO THE TREE. OPTIC DISC IS FASTENED IN SCLERAL OPENING BY CIRCULAR BORDER TISSUE & ANCHORAGE BY N.FIBERS AS ROOTS DO TO THE TREE. BORDERR TISSUE IS SOLELY SUPPLIED BY CILIARY CIRCULATION. BORDERR TISSUE IS SOLELY SUPPLIED BY CILIARY CIRCULATION. CILIARY CIRCULATION BEING LOW PRESSURE SYSTEM IS EASILY COMPROMOSED BY HIGH IOP & POOR SYSTEMIC CIRCULATION RESULTING IN ATROPHY OF BORDER TISSUE. CILIARY CIRCULATION BEING LOW PRESSURE SYSTEM IS EASILY COMPROMOSED BY HIGH IOP & POOR SYSTEMIC CIRCULATION RESULTING IN ATROPHY OF BORDER TISSUE.

SINKING OPTIC DISC TEMPORAL SINKING OF THE DISC WOULD STRETCH & CUT THE ARCUATE FIBERS AT THE SCLERAL EDGE TEMPORAL SINKING OF THE DISC WOULD STRETCH & CUT THE ARCUATE FIBERS AT THE SCLERAL EDGE MACULAR FIBERS ARE ALSO BEING DESTROYED. MACULAR FIBERS ARE ALSO BEING DESTROYED.

Nerve fibers in normal disc Peripheral fibers lie deeper and exit in the peripheral part of the disc. Macular fibers occupy superficial (closer to the vitreous) and central part of the disc. Although peripheral temporal fibers are shown below the macular fibers to explain the deeper location, they actually arch above and below the macular fibers. Peripheral fibers lie deeper and exit in the peripheral part of the disc. Macular fibers occupy superficial (closer to the vitreous) and central part of the disc. Although peripheral temporal fibers are shown below the macular fibers to explain the deeper location, they actually arch above and below the macular fibers.

EARLY STAGE OF GLAUCOMA Due to sinking of the optic disc the peripheral fibers are compressed, stretched and cut at the scleral edge (rim) earlier than the central fibers. Since arcuate fibers are peripheral fibers therefore they are destroyed in the early stages of glaucoma. Due to sinking of the optic disc the peripheral fibers are compressed, stretched and cut at the scleral edge (rim) earlier than the central fibers. Since arcuate fibers are peripheral fibers therefore they are destroyed in the early stages of glaucoma.

LATE STAGE OF GLAUCOMA Peripheral fibers are almost destroyed. As the peripheral fibers are being destroyed the macular fibers (blue) move closer to the edge. Since macular fibers are destroyed at the end therefore central vision is preserved till the end. As the central fibers move to the periphery the original cup is enlarged (de-cupping). Peripheral fibers are almost destroyed. As the peripheral fibers are being destroyed the macular fibers (blue) move closer to the edge. Since macular fibers are destroyed at the end therefore central vision is preserved till the end. As the central fibers move to the periphery the original cup is enlarged (de-cupping).

DUE TO TEMPORAL SINKING OF DISC THE ARCUATE FIBERS ARE STRETCHED AND CUT AT THE EDGE. NOTE THE CORRESPONDING LOSS ( WHITE AREA) IN THE DISC. THIS GIVES RISE TO THE DOUBLE ARCUATE FIELD DEFECT.

NIAGRA FALLS JUST AS THE WATER FLOW IS BEING CUT AT THE EDGE SIMILARLY N. FIBERS ARE BEING CUT AT SCLERAL EDGE.

CONCLUSION OPTIC DISC MAY NOT BE CUPPING BUT SINKING IN ITS ENTIRETY. OPTIC DISC MAY NOT BE CUPPING BUT SINKING IN ITS ENTIRETY. GLAUCOMA IS A MULTIFACTORIAL. GLAUCOMA IS A MULTIFACTORIAL. HTG IS OCULAR & NTG IS A SYSTEMIC DISEASE. HTG IS OCULAR & NTG IS A SYSTEMIC DISEASE. MORE THE RISK FACTORS PRESENT, MORE LIKELIHOOD OF DISEASE. MORE THE RISK FACTORS PRESENT, MORE LIKELIHOOD OF DISEASE. IN GLAUCOMA THE NERVE FIBERS ARE BEING CUT & DEPLETED. AT THE END STAGE THERE IS NO DISC AND NO NERVE FIBERS. IN GLAUCOMA THE NERVE FIBERS ARE BEING CUT & DEPLETED. AT THE END STAGE THERE IS NO DISC AND NO NERVE FIBERS.

THANK YOU FOR VISITING MY WEBSITE SYED S. HASNAIN M.D.